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{{short description|Time of offspring development in mother's body}}
{{dablink|This article focuses on human pregnancy. For pregnancy in mammals, see [[Pregnancy (mammals)]]. For a broader view, see [[gestation]]. For the medicine of pregnancy, see [[obstetrics]].}}
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[[Image:Expecting mother.jpg|thumb|A pregnant woman near the end of her term]]
{{about|pregnancy in humans|other mammals|Pregnancy (mammals)|fish|Pregnancy in fish}}
'''Pregnancy''' is the carrying of one or more [[embryo]]s or [[fetus]]es by [[female]] [[mammal]]s, including [[human]]s, inside their bodies. In a pregnancy, there can be multiple [[gestation]]s (for example, in the case of [[twin]]s, or [[Multiple birth|triplets]]). Human pregnancy is the most studied of all [[Pregnancy (mammals)|mammalian pregnancies]].
{{Redirect|Trimester (pregnancy)|other uses of 'trimester'|Trimester (disambiguation){{!}}Trimester}}
{{redirect|Pregnant|the My Hero episode|List of My Hero episodes#ep12}}
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{{Use dmy dates|date=March 2021}}
{{Infobox medical condition (new)
| name = Pregnancy
| synonym = Gestation
| image = PregnantWoman.jpg
| alt =
| caption = A woman in the third trimester of pregnancy
| field = [[Obstetrics]], [[midwifery]]
| symptoms = Missed periods, tender breasts, [[Morning sickness|nausea and vomiting]], hunger, frequent urination<ref name=NIH2013Sym/>
| complications = [[Miscarriage]], [[high blood pressure of pregnancy]], [[gestational diabetes]], [[iron-deficiency anemia]], [[hyperemesis gravidarum|severe nausea and vomiting]]<ref name="John2012">{{Cite book |url=https://books.google.com/books?id=4Sg5sXyiBvkC&pg=PA438 |title=The Johns Hopkins Manual of Gynecology and Obstetrics |date=2012 |publisher=Lippincott Williams & Wilkins |isbn=978-1-4511-4801-5 |edition=4 |page=438 |archive-url=https://web.archive.org/web/20170910181311/https://books.google.com/books?id=4Sg5sXyiBvkC&pg=PA438 |archive-date=10 September 2017 |url-status=live }}</ref><ref name=NIH2013Compli/>
| onset =
| duration = ~40&nbsp;weeks from the [[last menstrual period]] (38 weeks after conception)<ref name="NIH2013Def">{{Cite web |date=19 December 2013 |title=Pregnancy: Condition Information |url=http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/default.aspx |url-status=live |archive-url=https://web.archive.org/web/20150319163902/http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/default.aspx |archive-date=19 March 2015 |access-date=14 March 2015 |website=[[Eunice Kennedy Shriver National Institute of Child Health and Human Development]] }}</ref><ref name=Ab2011/>
| causes = [[Sexual intercourse]], [[assisted reproductive technology]]<ref name=She2016/>
| risks =
| diagnosis = [[Pregnancy test]]<ref name=NIH2012Diag/>
| differential =
| prevention = [[Birth control]] (including [[emergency contraception]])<ref name="Tay2011">{{cite journal | vauthors = Taylor D, James EA | title = An evidence-based guideline for unintended pregnancy prevention | journal = Journal of Obstetric, Gynecologic, and Neonatal Nursing | volume = 40 | issue = 6 | pages = 782–793 | date = 2011 | pmid = 22092349 | pmc = 3266470 | doi = 10.1111/j.1552-6909.2011.01296.x }}</ref>
| treatment = [[Prenatal care]],<ref name=NIH2013Prenatal/> [[abortion]]<ref name=Tay2011/>
| medication = [[Folic acid]], [[iron supplements]]<ref name=NIH2013Prenatal/><ref name="Keats2019">{{cite journal | vauthors = Keats EC, Haider BA, Tam E, Bhutta ZA | title = Multiple-micronutrient supplementation for women during pregnancy | journal = The Cochrane Database of Systematic Reviews | volume = 3 | pages = CD004905 | date = March 2019 | issue = 3 | pmid = 30873598 | pmc = 6418471 | doi = 10.1002/14651858.CD004905.pub6 }}</ref>
| prognosis =
| frequency = 213 million (2012)<ref name="Sed2014">{{cite journal | vauthors = Sedgh G, Singh S, Hussain R | title = Intended and unintended pregnancies worldwide in 2012 and recent trends | journal = Studies in Family Planning | volume = 45 | issue = 3 | pages = 301–314 | date = September 2014 | pmid = 25207494 | pmc = 4727534 | doi = 10.1111/j.1728-4465.2014.00393.x }}</ref>
| deaths = {{positive_decrease}} 230,600 (2016)<ref name="GBD2016">{{cite journal | title = Global, regional, and national age-sex specific mortality for 264 causes of death, 1980-2016: a systematic analysis for the Global Burden of Disease Study 2016 | journal = Lancet | volume = 390 | issue = 10100 | pages = 1151–1210 | date = September 2017 | pmid = 28919116 | pmc = 5605883 | doi = 10.1016/S0140-6736(17)32152-9 | collaboration = GBD 2016 Causes of Death Collaborators | vauthors = Naghavi M, Abajobir AA, Abbafati C, Abbas KM, Abd-Allah F, Abera SF, Aboyans V, Adetokunboh O, Afshin A, Agrawal A, Ahmadi A, Ahmed MB, Aichour AN, Aichour MT, Aichour I, Aiyar S, Alahdab F, Al-Aly Z, Alam K, Alam N, Alam T, Alene KA, Al-Eyadhy A, Ali SD, Alizadeh-Navaei R, Alkaabi JM, Alkerwi A, Alla F, Allebeck P, Allen C }}</ref>
}}


'''Pregnancy''' is the time during which one or more [[offspring]] develops ([[gestation|gestates]]) inside a [[woman]]'s [[uterus]] (womb).<ref name=NIH2013Def/><ref name="Mosby" /> A [[multiple birth|multiple pregnancy]] involves more than one offspring, such as with [[twin]]s.<ref>{{Cite book | vauthors = Wylie L |url= https://books.google.com/books?id=QgpOvSDxGGYC&pg=PA172 |title=Essential anatomy and physiology in maternity care |date=2005 |publisher=Churchill Livingstone |isbn=978-0-443-10041-3 |edition=Second |location=Edinburgh |page=172 |archive-url=https://web.archive.org/web/20170910181340/https://books.google.com/books?id=QgpOvSDxGGYC&pg=PA172 |archive-date=10 September 2017 |url-status=live }}</ref>
[[Childbirth]] usually occurs about 38 weeks from [[fertilization]], i.e. approximately 40 weeks from the start of the last [[menstruation]]. Thus, pregnancy lasts about nine months, although the exact definition of [[Beginning of pregnancy controversy|the English word “pregnancy”]] is a subject of controversy. The medical term for a pregnant [[female]] [[human]] is ''genetalian'', although this term is rarely used in common speech. The term ''[[embryo]]'' is used to describe the developing human during the initial weeks, and the term ''[[fetus]]'' is used from about two months of development until birth. A woman who is pregnant for the first time is known as a [[Gravidity|primigravida]] or "gravida 1", while a woman who has never been pregnant is known as "gravida 0". Similarly, the terms "[[Parity (medicine)|para 0]]", "para 1" and so on are used for the number of times a woman has given birth.


Pregnancy usually occurs by [[sexual intercourse]], but can also occur through [[assisted reproductive technology]] procedures.<ref name="She2016">{{Cite book | vauthors = Shehan CL |url= https://books.google.com/books?id=-gSeCAAAQBAJ&pg=PA406 |title=The Wiley Blackwell Encyclopedia of Family Studies, 4 Volume Set |date=2016 |publisher=John Wiley & Sons |isbn=978-0-470-65845-1 |page=406 |archive-url=https://web.archive.org/web/20170910181340/https://books.google.com/books?id=-gSeCAAAQBAJ&pg=PA406 |archive-date=10 September 2017 |url-status=live }}</ref> A pregnancy may end in a [[Live birth (human)|live birth]], a [[miscarriage]], an [[Abortion#Induced|induced abortion]], or a [[stillbirth]]. [[Childbirth]] typically occurs around 40&nbsp;weeks from the start of the [[Menstruation#Onset and frequency|last menstrual period]] (LMP), a span known as the [[Gestational age (obstetrics)|gestational age]].<ref name=NIH2013Def/><ref name=Ab2011/> This is just over nine&nbsp;months. Counting by [[Human fertilization#Fertilization age|fertilization age]], the length is about 38 weeks.<ref name=Ab2011/><ref name="Mosby">{{Cite book |url=https://books.google.com/books?id=_QGaoiFCIDMC&pg=PA1078 |title=Mosby's Pocket Dictionary of Medicine, Nursing & Health Professions - E-Book |vauthors=Mosby |publisher=[[Elsevier Health Sciences]] |year=2009 |isbn=978-0-323-06604-4 |page=1078}}</ref> Pregnancy is "the presence of an implanted human embryo or fetus in the uterus"; [[Implantation (embryology)|implantation]] occurs on average 8&ndash;9 days after fertilization.<ref>[https://www.mass.gov/info-details/mass-general-laws-c112-ss-12k Massachusetts General Laws c.112 § 12K: Definitions applicable to Secs. 12L to 12U], Commonwealth of Massachusetts, 2022</ref> An ''[[embryo]]'' is the term for the developing offspring during the first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term ''[[fetus]]'' is used until birth.<ref name="Ab2011">{{Cite book | vauthors = Abman SH |url=https://books.google.com/books?id=OyVDJoOIvbYC&pg=PA46 |title=Fetal and neonatal physiology |date=2011 |publisher=Elsevier/Saunders |isbn=978-1-4160-3479-7 |edition=4th |location=Philadelphia |pages=46–47 }}</ref>
In many societies' medical and legal definitions, human pregnancy is somewhat arbitrarily divided into three [[trimester]] periods, as a means to simplify reference to the different stages of [[fetal development]]. The first trimester period carries the highest risk of [[miscarriage]] (natural death of embryo or fetus). During the second trimester the development of the fetus can start to be monitored and diagnosed. The third trimester marks the beginning of viability, or the ability of the fetus to survive, with or without medical help, outside of the mother's womb. <!-- make footer reference (Though this can be controversial, depending on the age of the fetus and the discussed context.) -->
:''See also [[#Terms and definitions|Pregnancy terms and definitions]]


[[Signs and symptoms of pregnancy|Signs and symptoms of early pregnancy]] may include [[amenorrhea|missed periods]], tender breasts, [[morning sickness]] (nausea and vomiting), hunger, [[implantation bleeding]], and frequent urination.<ref name="NIH2013Sym">{{Cite web |date=12 July 2013 |title=What are some common signs of pregnancy? |url=http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/signs.aspx |url-status=live |archive-url=https://web.archive.org/web/20150319160741/http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/signs.aspx |archive-date=19 March 2015 |access-date=14 March 2015 |website=[[Eunice Kennedy Shriver National Institute of Child Health and Human Development]] }}</ref> Pregnancy may be confirmed with a [[pregnancy test]].<ref name="NIH2012Diag">{{Cite web |date=30 November 2012 |title=How do I know if I'm pregnant? |url=http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/know.aspx |url-status=live |archive-url=https://web.archive.org/web/20150402165852/http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/know.aspx |archive-date=2 April 2015 |access-date=14 March 2015 |website=[[Eunice Kennedy Shriver National Institute of Child Health and Human Development]] }}</ref> Methods of [[birth control]]—or, more accurately, ''contraception''—are used to avoid pregnancy.
== Determining the start of pregnancy and predicting date of birth ==
{{seealso|Gestational age}}
Before pregnancy begins, a female [[oocyte]] ([[ovum|egg]]) must join, by [[spermatozoon]] in a process referred to in medicine as "[[fertilization]]", or commonly known as "conception" (though the [[Beginning of pregnancy controversy#How the Controversy Began|definition of the English word "conception" is somewhat controversial]]). Fertilization occurs usually through the act of [[sexual intercourse]], in which a man [[ejaculation|ejaculates]] inside a woman, thus releasing his sperm; however, the advent of [[artificial insemination]] has made it possible for women to become pregnant if pre-existing medical conditions from either the woman or the man make fertilization through sexual intercourse difficult, or if a woman chooses to become pregnant without a male partner, for any number of reasons. Though pregnancy begins at implantation, it is often convenient to date from the first day of a woman's Last Menstrual Period (LMP). This is used to calculate the Expected Date of Delivery (EDD).


Pregnancy is divided into three trimesters of approximately three months each. The [[first trimester]] includes conception, which is when the sperm fertilizes the egg. The [[fertilized egg]] then travels down the [[fallopian tube]] and attaches to the inside of the [[uterus]], where it begins to form the [[embryo]] and [[placenta]]. During the first trimester, the possibility of miscarriage (natural death of embryo or fetus) is at its highest. Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies can [[Fetal viability|survive outside of the uterus]] if [[Neonatal intensive care unit|provided with high-quality medical care]], though babies born at this time will likely experience serious health complications such as heart and respiratory problems and long-term intellectual and developmental disabilities.
Traditionally a human pregnancy is considered to last approximately 40 weeks (280 days) from the LMP, or 38 weeks (266 days) from the date of fertilization. The 38 weeks of gestation is 9 [[lunar month]]s. In the more familiar [[Gregorian calendar]], the 40 weeks dating from the LMP is equivalent to a little more than nine months and six days, and this forms the basis of [[Naegele's rule]] of approximating the EDD. A pregnancy is considered to have reached term between 37 and 43 weeks from the beginning of the last [[menstruation]]. Babies born before the 37 week mark are considered [[Premature birth|premature]], while babies born after the 43 week mark are considered [[Postmature birth|postmature]].


[[Prenatal care]] improves pregnancy outcomes.<ref name=NIH2013Prenatal/> [[Nutrition and pregnancy|Nutrition]] during pregnancy is important to ensure healthy growth of the fetus.<ref name="Handbook">{{Cite book |title=Handbook of Nutrition and Pregnancy |date=2008 |publisher=Humana Press |isbn=978-1-59745-112-3 | veditors = Lammi-Keefe CJ, Couch SC, Philipson EH |series=Nutrition and health |location=Totowa, NJ |page=28 |doi=10.1007/978-1-59745-112-3 }}</ref> Prenatal care may also include avoiding [[recreational drug]]s (including [[Smoking and pregnancy|tobacco]] and [[Fetal alcohol spectrum disorder|alcohol]]), taking regular exercise, having [[blood test]]s, and regular [[physical examination]]s.<ref name="NIH2013Prenatal">{{Cite web |date=12 July 2013 |title=What is prenatal care and why is it important? |url=http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/prenatal-care.aspx |url-status=live |archive-url=https://web.archive.org/web/20150402095646/http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/prenatal-care.aspx |archive-date=2 April 2015 |access-date=14 March 2015 |website=[[Eunice Kennedy Shriver National Institute of Child Health and Human Development]] }}</ref> [[Complications of pregnancy]] may include [[hypertensive disease of pregnancy|disorders of high blood pressure]], [[gestational diabetes]], [[iron-deficiency anemia]], and [[hyperemesis gravidarum|severe nausea and vomiting]].<ref name="NIH2013Compli">{{Cite web |date=12 July 2013 |title=What are some common complications of pregnancy? |url=http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/complications.aspx |url-status=live |archive-url=https://web.archive.org/web/20150226221631/http://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/Pages/complications.aspx |archive-date=26 February 2015 |access-date=14 March 2015 |website=[[Eunice Kennedy Shriver National Institute of Child Health and Human Development]] }}</ref> In the ideal childbirth, labor begins on its own "at term".<ref name="ACOGfive-2">{{Citation |last=American Congress of Obstetricians and Gynecologists |title=Five Things Physicians and Patients Should Question |date=February 2013 |url=http://www.choosingwisely.org/doctor-patient-lists/american-college-of-obstetricians-and-gynecologists/ |work=[[Choosing Wisely]]: an initiative of the [[ABIM Foundation]] |archive-url=https://web.archive.org/web/20130901094916/http://www.choosingwisely.org/doctor-patient-lists/american-college-of-obstetricians-and-gynecologists/ |publisher=[[American Congress of Obstetricians and Gynecologists]] |access-date=1 August 2013 |archive-date=1 September 2013 |author-link=American Congress of Obstetricians and Gynecologists |url-status=live}}</ref> Babies born before 37 weeks are "[[preterm]]" and at higher risk of health problems such as [[cerebral palsy]].<ref name=NIH2013Def/> Babies born between weeks 37 and 39 are considered "early term" while those born between weeks 39 and 41 are considered "full term".<ref name=NIH2013Def/> Babies born between weeks 41 and 42 weeks are considered "late-term" while after 42 weeks they are considered "[[Postterm pregnancy|post-term]]".<ref name=NIH2013Def/> [[Childbirth|Delivery]] before 39 weeks by [[labor induction]] or [[caesarean section]] is not recommended unless required for other medical reasons.<ref name="WHO2014">{{Cite web |last=World Health Organization |date=November 2014 |title=Preterm birth Fact sheet N°363 |url=https://www.who.int/mediacentre/factsheets/fs363/en/ |url-status=live |archive-url=https://web.archive.org/web/20150307050438/http://www.who.int/mediacentre/factsheets/fs363/en/ |archive-date=7 March 2015 |access-date=6 March 2015 |website=who.int }}</ref>
Though these are the averages, the actual length of pregnancy depends on various factors. For example, the first pregnancy tends to last longer than subsequent pregnancies. Fewer than 10% of births occur on the due date; 50% of births are within a week of the due date, and almost 90% within two weeks. The due date is typically calculated as 40 weeks from the last menstrual period.


{{TOC limit}}
An accurate date of fertilization is important, because it is used in calculating the results of various [[Prenatal diagnosis|prenatal tests]] (for example, in the [[triple test]]). A decision may be made to [[Induction (birth)|induce]] labour if a fetus is perceived to be overdue. Due dates are only a rough estimate, and the process of accurately dating a pregnancy is complicated by the fact that not all women have 28 day menstrual cycles, or ovulate on the 14th day following their last menstrual period. Approximately 3.6% of all women deliver on the due date predicted by LMP, and 4.7% give birth on the day predicted by sonograph.{{Fact|date=April 2007}}<!--This contradicts what is written above. The discrepancy needs to be resolved.-->


==Terminology==
The beginning of pregnancy may be detected in a number of ways, including various pregnancy tests which detect hormones generated by the newly-formed [[placenta]]. Clinical blood and urine tests can detect pregnancy soon after implantation, which is as early as 6-8 days after fertilization. Home [[pregnancy test]]s are personal [[urine]] tests, which normally cannot detect a pregnancy until at least 12-15 days after fertilization. Both clinical and home tests can only detect the state of pregnancy, and cannot detect its age.
[[File:Anatomia uteri humani gravidi V00001 00000002.tif|thumb|[[William Hunter (anatomist)|William Hunter]], ''Anatomia uteri humani gravidi tabulis illustrata'', 1774|alt=Title page from an 18th-century book about pregnancy]]
Associated terms for pregnancy are ''gravid'' and ''parous''. ''Gravidus'' and ''gravid'' come from the [[Latin]] word meaning "heavy" and a pregnant female is sometimes referred to as a ''gravida''.<ref name="MFD">{{Cite web |title=definition of gravida |url=http://medical-dictionary.thefreedictionary.com/gravida |access-date=17 January 2008 |publisher=[[TheFreeDictionary.com|The Free Dictionary]]}}</ref> ''[[Gravidity and parity|Gravidity]]'' refers to the number of times that a female has been pregnant. Similarly, the term ''[[Gravidity and parity#Parity|parity]]'' is used for the number of times that a female carries a pregnancy to a [[fetal viability|viable stage]].<ref name="Patient">{{Cite web |title=Gravidity and Parity Definitions (Implications in Risk Assessment) |url=https://patient.info/doctor/gravidity-and-parity-definitions-and-their-implications-in-risk-assessment |url-status=live |archive-url=https://web.archive.org/web/20161212152618/http://patient.info/doctor/gravidity-and-parity-definitions-and-their-implications-in-risk-assessment |archive-date=12 December 2016 |website=patient.info }}</ref> [[Twins]] and other multiple births are counted as one pregnancy and birth.


A woman who has never been pregnant is referred to as a ''nulligravida.'' A woman who is (or has been only) pregnant for the first time is referred to as a ''primigravida'',<ref name=TMHP>{{cite-TMHP|Primipara}}, page 596.</ref> and a woman in subsequent pregnancies as a ''[[multigravida]]'' or as ''multiparous.''<ref name="MFD" /><ref>{{Cite web |title=Definition of nulligravida |url=http://medical.merriam-webster.com/medical/nulligravida |archive-url=https://web.archive.org/web/20080908010608/http://medical.merriam-webster.com/medical/nulligravida |archive-date=8 September 2008 |access-date=9 March 2012 |publisher=[[Merriam-Webster, Incorporated]] }}</ref> Therefore, during a second pregnancy a woman would be described as ''gravida 2, para 1'' and upon live delivery as ''gravida 2, para 2.'' In-progress pregnancies, [[abortion]]s, [[miscarriage]]s and/or [[stillbirth]]s account for parity values being less than the gravida number. Women who have never carried a pregnancy more than 20 weeks are referred to as ''nulliparous''.<ref>{{Cite web |date=18 November 2000 |title=Nulliparous definition |url=http://www.medterms.com/script/main/art.asp?articlekey=15259 |url-status=live |archive-url=https://web.archive.org/web/20090709225422/http://www.medterms.com/script/main/art.asp?articlekey=15259 |archive-date=9 July 2009 |publisher=MedicineNet, Inc }}</ref>
In the post-implantation phase, the [[blastocyst]] secretes a hormone named [[human chorionic gonadotropin]] which in turn, stimulates the [[corpus luteum]] in the woman's ovary to continue producing [[progesterone]]. This acts to maintain the lining of the uterus so that the embryo will continue to be nourished. The glands in the lining of the uterus will swell in response to the blastocyst, and capillaries will be stimulated to grow in that region. This allows the blastocyst to receive vital nutrients from the woman. Pregnancy tests detect the presence of human chorionic gonadotropin.
An early [[medical ultrasonography|sonograph]] can determine the age of the pregnancy fairly accurately. In practice, doctors typically express the age of a pregnancy (i.e. an "age" for an [[embryo]]) in terms of "menstrual date" based on the first day of a woman's last menstrual period, as the woman reports it. Unless a woman's recent [[human sexual behavior|sexual activity]] has been limited, the exact date of fertilization is unknown. Absent symptoms such as [[morning sickness]], often the only visible sign of a pregnancy is an interruption of her normal monthly menstruation cycle, (i.e. a "late period"). Hence, the "menstrual date" is simply a common educated estimate for the age of a fetus, which is an average of two weeks later than the first day of the woman's last menstrual period. (The [[margin of error]] is 0 to 30 days after last menstruation, hence a 14 day average.) The term "conception date" may sometimes be used when that date is more certain, though even medical professionals can be imprecise with their use of the two distinct terms. The due date can be calculated by using [[Naegele's rule]].


A pregnancy is considered ''term'' at 37 weeks of gestation. It is ''preterm'' if less than 37 weeks and ''postterm'' at or beyond 42 weeks of gestation. American College of Obstetricians and Gynecologists have recommended further division with ''early term'' 37 weeks up to 39 weeks, ''full term'' 39 weeks up to 41 weeks, and ''late term'' 41 weeks up to 42 weeks.<ref>{{Cite web |title=Definition of Term Pregnancy – ACOG |url=https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Definition-of-Term-Pregnancy |access-date=2019-09-27 |website=www.acog.org}}</ref> The terms ''preterm'' and ''postterm'' have largely replaced earlier terms of ''premature'' and ''postmature''. ''Preterm'' and ''postterm'' are defined above, whereas ''premature'' and ''postmature'' have historical meaning and relate more to the infant's size and state of development rather than to the stage of pregnancy.<ref>{{Cite web |title=Definition of Premature birth |url=http://www.medterms.com/script/main/art.asp?articlekey=11895 |url-status=live |archive-url=https://web.archive.org/web/20090709225826/http://www.medterms.com/script/main/art.asp?articlekey=11895 |archive-date=9 July 2009 |access-date=16 January 2008 |publisher=Medicine.net }}</ref><ref>{{Cite encyclopedia |title=Premature Infant |encyclopedia=Disease & Conditions Encyclopedia |publisher=Discovery Communications, LLC. |url=http://health.discovery.com/encyclopedias/illnesses.html?article=2728 |access-date=16 January 2008 |date=22 September 2006 |archive-url=https://web.archive.org/web/20080119213709/http://health.discovery.com/encyclopedias/illnesses.html?article=2728 |archive-date=19 January 2008 |author=Lama Rimawi, MD |url-status=live }}</ref>
===Pregnancy symptoms===
Symptoms of pregnancy may vary from woman to woman and even pregnancy to pregnancy. While not all will occur with every pregnancy and some symptoms are in fact rare, following is a list of some of the potential symptoms of pregnancy.


==Demographics and statistics==
*Implantation, the female body begins to adjust to prenatal stage. There may be some twinge associated with implantation. (Generally 7-10 after fertilization.)
About 213 million pregnancies occurred in 2012, of which, 190 million (89%) were in the [[developing world]] and 23 million (11%) were in the developed world.<ref name=Sed2014/> The number of pregnancies in women aged between 15 and 44 is 133 per 1,000 women.<ref name="Sed2014">{{cite journal | vauthors = Sedgh G, Singh S, Hussain R | title = Intended and unintended pregnancies worldwide in 2012 and recent trends | journal = Studies in Family Planning | volume = 45 | issue = 3 | pages = 301–314 | date = September 2014 | pmid = 25207494 | pmc = 4727534 | doi = 10.1111/j.1728-4465.2014.00393.x }}</ref> About 10% to 15% of recognized pregnancies end in [[miscarriage]].<ref name="John2012">{{Cite book |url=https://books.google.com/books?id=4Sg5sXyiBvkC&pg=PA438 |title=The Johns Hopkins Manual of Gynecology and Obstetrics |date=2012 |publisher=Lippincott Williams & Wilkins |isbn=978-1-4511-4801-5 |edition=4 |page=438 |archive-url=https://web.archive.org/web/20170910181311/https://books.google.com/books?id=4Sg5sXyiBvkC&pg=PA438 |archive-date=10 September 2017 |url-status=live }}</ref> In 2016, [[complications of pregnancy]] resulted in 230,600 [[maternal death]]s, down from 377,000 deaths in 1990.<ref name="GBD2016" /> Common causes include [[maternal bleeding|bleeding]], [[Postpartum infections|infections]], [[Hypertensive disease of pregnancy|hypertensive diseases of pregnancy]], [[obstructed labor]], miscarriage, abortion, or [[ectopic pregnancy]].<ref name=GBD2016/> Globally, 44% of pregnancies are [[Unintended pregnancy|unplanned]].<ref name=Bea2018/> Over half (56%) of unplanned pregnancies are aborted.<ref name="Bea2018">{{cite journal | vauthors = Bearak J, Popinchalk A, Alkema L, Sedgh G | title = Global, regional, and subregional trends in unintended pregnancy and its outcomes from 1990 to 2014: estimates from a Bayesian hierarchical model | journal = The Lancet. Global Health | volume = 6 | issue = 4 | pages = e380–e389 | date = April 2018 | pmid = 29519649 | pmc = 6055480 | doi = 10.1016/S2214-109X(18)30029-9 }}</ref> Among unintended pregnancies in the United States, 60% of the women used [[birth control]] to some extent during the month pregnancy began.<ref>{{Cite book | vauthors = Hurt KJ, Guile MW, Bienstock JL, Fox HE, Wallach EE |url=https://books.google.com/books?id=4Sg5sXyiBvkC&pg=PR232 |title=The Johns Hopkins manual of gynecology and obstetrics |date=2012-03-28 |publisher=Wolters Kluwer Health / Lippincott Williams & Wilkins |isbn=978-1-60547-433-5 |edition=4th |location=Philadelphia |pages=382 }}</ref>
*Delayed or difference in menstruation.
*Minor vaginal bleeding (spotting).
*Swollen or tender breast, minor lactation in third trimester.
*Fatigue, also may experience sleeplessness.
*Nausea, sometimes accompanied by vomiting, esp. the first trimester, most likely to start at around 7 weeks. ([[morning sickness]]).
*Lower backaches, but few pregnant women had serious back pain.
*Headaches, some may reach migraine level in others.
*Long frequent hiccuping spells.<ref>{{cite web | year = 1999 | month = December | url = http://www.parenting.com/parenting/pregnancy/article/0,19840,647554,00.html | title = Strange But True Pregnancy Tales | format = | work = | pages = 6 | publisher = Parenting | accessdate =}}</ref>
*Enlarged feet and hands, or expanded buttocks.
*Frequent urination, sometimes random "drips" of urine.
*Constipation, but a few encounter random defecation.
*Food cravings, or increased appetite.
*Rational fear of increasingly imposing burden.
*Heartburn or upset stomach, but rarely may accompany vomiting.
*Stomach/intestinal gas, may be frequently flatulent or belch.
*Difficulty in walking and balance, some may be put on bedrest.
*Difficulty with contact or vision prescriptions.


==Signs and symptoms==
Symptoms of pregnancy do not allow for a pregnancy diagnosis because each of these symptoms has the potential to be explained by other reasons (e.g. missing a period because of stress).
{{Main|Signs and symptoms of pregnancy}}
{{Further|Complications of pregnancy}}
[[File:Melasmablemish.jpg|thumb|[[Melasma]]: pigment changes to the face due to pregnancy]][[File:PregnancyinCrossSection.jpg|thumb|In the later part of pregnancy the uterus takes up much of the abdomen.]]
The usual [[signs and symptoms of pregnancy]] do not significantly interfere with [[activities of daily living]] or pose a health-threat to the [[mother]] or baby. However, [[Complications of pregnancy|pregnancy complications]] can cause other more severe symptoms, such as those associated with [[anemia]].


Common signs and symptoms of pregnancy include:
Pregnancy does have a minor, but noticed psychological effect by hormonal changes and chemical reactions in some women, known as "mood swings" that are controlled. She may experience periods of enhanced content, excitement or fickleness, and melancholy, anxiety or angst, but it often depends on how the pregnant woman views herself and attitudes on her condition in various ways.
* [[Fatigue (medicine)|Tiredness]]
* [[Morning sickness]]
* [[Constipation]]
* [[Pelvic girdle pain]]
* [[Back pain#Pregnancy|Back pain]]
* [[Braxton Hicks contractions]]. Occasional, irregular, and often painless contractions that occur several times per day.
* [[Peripheral edema]] swelling of the lower limbs. Common complaint in advancing pregnancy. Can be caused by [[inferior vena cava syndrome]] resulting from compression of the [[inferior vena cava]] and pelvic veins by the [[uterus]] leading to increased [[Hydrostatic pressure#Medicine|hydrostatic pressure]] in lower extremities.
* [[Hypotension|Low blood pressure]] often caused by compression of both the inferior vena cava and the [[abdominal aorta]] ([[aortocaval compression syndrome]]).
* [[Increased urinary frequency]]. A common complaint, caused by increased intravascular volume, elevated [[glomerular filtration rate]], and compression of the [[urinary bladder|bladder]] by the expanding uterus.
* [[Urinary tract infection#Pregnant women|Urinary tract infection]]<ref>{{Cite web |last=Merck |title=Urinary tract infections during pregnancy |url=http://www.merckmanuals.com/home/womens_health_issues/pregnancy_complicated_by_disease/urinary_tract_infections_during_pregnancy.html |url-status=live |archive-url=https://web.archive.org/web/20111110140608/http://www.merckmanuals.com/home/womens_health_issues/pregnancy_complicated_by_disease/urinary_tract_infections_during_pregnancy.html |archive-date=10 November 2011 |website=Merck Manual Home Health Handbook }}</ref>
* [[Varicose veins]]. Common complaint caused by relaxation of the venous [[smooth muscle]] and increased intravascular pressure.
* [[Hemorrhoids]] (piles). Swollen [[Rectal venous plexus|veins at or inside the anal area]]. Caused by impaired venous return, straining associated with constipation, or increased intra-abdominal pressure in later pregnancy.<ref name="CE-Vazquez">{{cite journal | vauthors = Vazquez JC | title = Constipation, haemorrhoids, and heartburn in pregnancy | journal = BMJ Clinical Evidence | volume = 2010 | pages = 1411 | date = August 2010 | pmid = 21418682 | pmc = 3217736 }}</ref>
* [[Regurgitation (digestion)|Regurgitation]], [[heartburn]], and [[nausea]].
* [[Stretch marks#Pregnancy|Stretch marks]]
* [[Breast tenderness]] is common during the first trimester, and is more common in women who are pregnant at a young age.<ref>[https://www.nlm.nih.gov/medlineplus/ency/article/003152.htm MedlinePlus > Breast pain] {{webarchive|url=https://archive.today/20120805080233/http://www.nlm.nih.gov/medlineplus/ency/article/003152.htm |date=5 August 2012 }} Update Date: 31 December 2008. Updated by: David C. Dugdale, Susan Storck. Also reviewed by David Zieve.</ref>
* [[Melasma]], also known as the mask of pregnancy, is a discoloration, most often of the face. It usually begins to fade several months after giving birth.


===Terminology===
==Timeline==
{| class="wikitable"
There are likewise finer distinctions between the concepts of fertilization and the actual state of pregnancy, which starts with implantation. In a normal pregnancy, the fertilization of the egg usually will have occurred in the [[Fallopian tube]]s or in the [[uterus]]. (Often, an egg may become fertilized yet fail to become implanted in the uterus.) If the pregnancy is the result of [[in-vitro fertilization]], the fertilization will have occurred in a [[Petri dish]], after which pregnancy begins when one or more zygotes implant after being transferred by a [[physician]] into the woman's uterus.
|+Comparison of dating systems for a typical pregnancy
! scope="col" |Event
! scope="col" width="200em" |Gestational age
<small>(from the start of the [[last menstrual period]])</small>
! scope="col" |Fertilization age
! scope="col" |Implantation age
|-
|[[Menstrual period]] begins
|Day 1 of pregnancy
|style="background:beige" |''Not pregnant''
|style="background:beige" |''Not pregnant''
|-
|Has [[Sexual intercourse|sex]] and [[Ovulation|ovulates]]
|2 weeks pregnant
|style="background:beige" |''Not pregnant''
|style="background:beige" |''Not pregnant''
|-
|[[Fertilisation|Fertilization]]; [[cleavage stage]] begins<ref name="Nair">{{Cite book | vauthors = Nair M, Kumar B |title=Fetal Medicine |date=2016-04-07 |publisher=Cambridge University Press |isbn=978-1-107-06434-8 | veditors = Kumar B, Alfirevic Z |pages=54–59 |chapter=Embryology for fetal medicine |chapter-url=https://books.google.com/books?id=Ie67CwAAQBAJ&dq=%22this+equates+to+a+period+of+just+over+9+calendar+months%22&pg=PA53}}</ref>
|Day 15<ref name="Nair" />
|Day 1<ref name="Nair" /><ref name="Mishra">{{Cite book |url=https://books.google.com/books?id=UTjvDwAAQBAJ |title=Langman's Medical Embryology |date=2019-08-07 |publisher=Wolters kluwer india Pvt Ltd |isbn=978-93-88696-53-1 | veditors = Mishra S |pages=48}}</ref>
|style="background:beige" |''[[Beginning of pregnancy controversy|Not pregnant]]''
|-
|[[Implantation (human embryo)|Implantation]] of [[blastocyst]] begins
|Day 20
|Day 6<ref name="Nair" /><ref name="Mishra" />
|Day 0
|-
|Implantation finished
|Day 26
|Day 12<ref name="Nair" /><ref name="Mishra" />
|Day 6 (or [[Beginning of pregnancy controversy|Day 0]])
|-
|[[Human embryonic development|Embryo]] stage begins; also, first [[missed period]]
|4 weeks
|Day 15<ref name="Nair" />
|Day 9
|-
|[[Cardiogenesis|Primitive heart function]] can be [[Transvaginal ultrasound|detected]]
|5 weeks, 5 days<ref name="Nair" />
|Day 26<ref name="Nair" />
|Day 20
|-
|[[Fetus|Fetal stage]] begins
|10 weeks, 1 day<ref name="Nair" />
|8 weeks, 1 day<ref name="Nair" />
|7 weeks, 2 days
|-
|First trimester ends
|13 weeks
|11 weeks
|10 weeks
|-
|Second trimester ends
|26 weeks
|24 weeks
|23 weeks
|-
|[[Childbirth]]
|39–40 weeks
|37–38 weeks<ref name="Mishra" />{{Rp|page=108}}
|36–37 weeks
|}
The [[chronology]] of pregnancy is, unless otherwise specified, generally given as [[Gestational age (obstetrics)|gestational age]], where the starting point is the beginning of the woman's [[last menstrual period]] (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. This model means that the woman is counted as being "pregnant" two weeks before [[conception (biology)|conception]] and three weeks before [[Implantation (human embryo)|implantation]]. Sometimes, timing may also use the [[fertilization age]], which is the age of the embryo since conception.


===Start of gestational age===
In the context of political debates regarding a proper [[definition of life]], the terminology of pregnancy can be confusing. Because precise assessment of a pregnancy as being at the "embryo" or "fetus" stage is usually undeterminable, the terms (though more clinically precise) are less commonly used than terms like "baby" or "child." The medically and politically neutral term which remains is simply "pregnancy," though this can be problematic as it only refers indirectly to the embryo or fetus. In the context of personal treatment, [[bedside manner]] generally dictates that doctors make sparse use of clinical language like "fetus" and "embryo," and instead simply refer to the developing child as a "[[baby]]", though this is not medically accurate.
{{Main|Gestational age}}
The [[American Congress of Obstetricians and Gynecologists]] recommends the following methods to calculate gestational age:<ref name=acog2012>[http://www.acog.org/About_ACOG/ACOG_Departments/Patient_Safety_and_Quality_Improvement/~/media/Departments/Patient%20Safety%20and%20Quality%20Improvement/201213IssuesandRationale-GestationalAgeTerm.pdf Obstetric Data Definitions Issues and Rationale for Change – Gestational Age & Term] {{webarchive|url=https://web.archive.org/web/20131106111500/http://www.acog.org/About_ACOG/ACOG_Departments/Patient_Safety_and_Quality_Improvement/~/media/Departments/Patient%20Safety%20and%20Quality%20Improvement/201213IssuesandRationale-GestationalAgeTerm.pdf |date=6 November 2013 }} from Patient Safety and Quality Improvement at [[American Congress of Obstetricians and Gynecologists]]. Created November 2012.</ref>
* Directly calculating the days since the beginning of the [[Menstrual cycle|last menstrual period]].
* Early [[obstetric ultrasound]], comparing the size of an [[human embryo|embryo]] or [[fetus]] to that of a [[reference group]] of pregnancies of known gestational age (such as calculated from last menstrual periods), and using the mean gestational age of other embryos or fetuses of the same size. If the gestational age as calculated from an early ultrasound is contradictory to the one calculated directly from the last menstrual period, it is still the one from the early ultrasound that is used for the rest of the pregnancy.<ref name=acog2012/>
* In case of [[in vitro fertilization]], calculating days since [[oocyte retrieval]] or [[co-incubation]] and adding 14 days.<ref>{{cite journal | vauthors = Tunón K, Eik-Nes SH, Grøttum P, Von Düring V, Kahn JA | title = Gestational age in pregnancies conceived after in vitro fertilization: a comparison between age assessed from oocyte retrieval, crown-rump length and biparietal diameter | journal = Ultrasound in Obstetrics & Gynecology | volume = 15 | issue = 1 | pages = 41–46 | date = January 2000 | pmid = 10776011 | doi = 10.1046/j.1469-0705.2000.00004.x | s2cid = 20029116 | doi-access = free }}</ref>


===Detection===
===Trimesters===
Pregnancy is divided into three trimesters, each lasting for approximately three months.<ref name=NIH2013Def/> The exact length of each trimester can vary between sources.
The early stages of pregnancy are often discovered by using a [[pregnancy test]]. There is no possible way to detect pregnancy until the 22nd day after fertilization. In the post-implantation phase the [[blastocyst]] secretes a hormone named [[human chorionic gonadotropin]] which in turn, stimulates the [[corpus luteum]] in the woman's ovary to continue producing [[progesterone]]. This acts to maintain the lining of the uterus so that the embryo will continue to be nourished. The glands in the lining of the uterus will swell in response to the blastocyst, and capillaries will be stimulated to grow in that region. This allows the blastocyst to receive vital nutrients from the woman. Pregnancy tests detect the presence of human chorionic gonadotropin.
{{anchor|First trimester}}{{anchor|Second trimester}}{{anchor|Third trimester}}
*The '''first trimester''' begins with the start of gestational age as described above, that is, the beginning of week 1, or 0 weeks + 0 days of gestational age (GA). It ends at week 12 (11 weeks + 6 days of GA)<ref name=NIH2013Def/> or end of week 14 (13 weeks + 6 days of GA).<ref name="UCSF">{{Cite web |title=Pregnancy – the three trimesters |url=https://www.ucsfhealth.org/conditions/pregnancy/trimesters |access-date=2019-11-30 |website=[[University of California San Francisco]]}}</ref>
*The '''second trimester''' is defined as starting, between the beginning of week 13 (12 weeks +0 days of GA)<ref name=NIH2013Def/> and beginning of week 15 (14 weeks + 0 days of GA).<ref name=UCSF/> It ends at the end of week 27 (26 weeks + 6 days of GA)<ref name=UCSF/> or end of week 28 (27 weeks + 6 days of GA).<ref name=NIH2013Def/>
*The '''third trimester''' is defined as starting, between the beginning of week 28 (27 weeks + 0 days of GA)<ref name=UCSF/> or beginning of week 29 (28 weeks + 0 days of GA).<ref name=NIH2013Def/> It lasts until [[childbirth]].
[[File:Pregnancy timeline.png|center|thumb|700px|Timeline of pregnancy, including (from top to bottom): Trimesters, embryo/fetus development, [[gestational age]] in weeks and months, viability and maturity stages]]


==Timeline of a typical pregnancy==
===Estimation of due date===
[[File:Distribution of gestational age at childbirth.jpg|thumb|Distribution of [[gestational age]] at childbirth among singleton live births, given both when gestational age is estimated by first trimester ultrasound and directly by last menstrual period.<ref name="hoffman2008">{{cite journal | vauthors = Hoffman CS, Messer LC, Mendola P, Savitz DA, Herring AH, Hartmann KE | title = Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester | journal = Paediatric and Perinatal Epidemiology | volume = 22 | issue = 6 | pages = 587–596 | date = November 2008 | pmid = 19000297 | doi = 10.1111/j.1365-3016.2008.00965.x | author-link5 = Amy H. Herring }}</ref> Roughly 80% of births occur between 37 and 41 weeks of gestational age.]]
:''The term '''trimester''' redirects here. For the term trimester used in academic settings, see [[Academic term]]''
{{Main|Estimated date of delivery}}
Pregnancy is typically broken into three periods, or trimesters, each of about three months. While there are no hard and fast rules, these distinctions are useful in describing the changes that take place over time.
[[Estimated date of delivery|Due date estimation]] basically follows two steps:
* Determination of which time point is to be used as [[Origin (number)|origin]] for [[Gestational age (obstetrics)|gestational age]], as described in the section above.
* Adding the estimated gestational age at childbirth to the above time point. Childbirth on average occurs at a gestational age of 280 days (40 weeks), which is therefore often used as a standard estimation for individual pregnancies.<ref name="mayo">{{cite web |title=Pregnancy week by week |url=https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20045997 |publisher=Mayo Clinic |access-date=8 July 2023 |date=3 June 2022}}</ref> However, alternative durations as well as more individualized methods have also been suggested.


The [[American College of Obstetricians and Gynecologists]] divides full term into three divisions:<ref>{{cite web |title=ement Health IT and Clinical Informatics reVITALize: Obstetrics Data Definitions reVITALize: Obstetrics Data Definitions |url=https://www.acog.org/practice-management/health-it-and-clinical-informatics/revitalize-obstetrics-data-definitions |website=ACOG |access-date=November 27, 2022}}</ref>
===First trimester===
[[Image:Pregnancy comparison.jpg|thumb|left|Comparison of growth of the fetus between 26 weeks and 40 weeks gestation.]]
Traditionally, doctors have measured pregnancy from a number of convenient points, including the day of last menstruation, ovulation, fertilization, implantation and chemical detection. In medicine, pregnancy is often defined as beginning when the developing [[embryo]] becomes [[implantation|implanted]] into the [[endometrium|endometrial]] lining of a [[woman]]'s [[uterus]]. In some cases where complications may have arisen, the fertilized egg might implant itself in the [[fallopian tubes]] or the [[cervix]], causing an [[ectopic pregnancy]]. Most pregnant women do not have any specific signs or symptoms of implantation, although it is not uncommon to experience light bleeding at implantation. Some women will also experience cramping during their first trimester. This is usually of no concern unless there is spotting or bleeding as well. The outer layers of the embryo grow and form a [[placenta]], for the purpose of receiving essential [[nutrients]] through the [[uterine]] wall, or [[endometrium]]. The [[umbilical cord]] in a newborn child consists of the remnants of the connection to the placenta. The developing embryo undergoes tremendous growth and changes during the process of [[fetal development|embryonic and fetal development]].


*Early-term: 37 weeks and 0 days through 38 weeks and 6 days
[[Morning sickness]] afflicts about seventy percent of all pregnant women, typically only in the first trimester.{{Fact|date=February 2007}} Most [[miscarriage]]s occur during this period.
*Full-term: 39 weeks and 0 days through 40 weeks and 6 days
*Late-term: 41 weeks and 0 days through 41 weeks and 6 days
*Post-term: greater than or equal to 42 weeks and 0 days
''Naegele's rule'' is a standard way of calculating the due date for a pregnancy when assuming a gestational age of 280 days at childbirth. The rule estimates the expected date of delivery (EDD) by adding a year, subtracting three months, and adding seven days to the origin of gestational age. Alternatively there are [[mobile app]]s, which essentially always give consistent estimations compared to each other and correct for [[leap year]], while pregnancy wheels made of paper can differ from each other by 7 days and generally do not correct for leap year.<ref name="pmid24036402">{{cite journal | vauthors = Chambliss LR, Clark SL | title = Paper gestational age wheels are generally inaccurate | journal = American Journal of Obstetrics and Gynecology | volume = 210 | issue = 2 | pages = 145.e1–145.e4 | date = February 2014 | pmid = 24036402 | doi = 10.1016/j.ajog.2013.09.013 }}</ref>


Furthermore, actual childbirth has only a certain probability of occurring within the limits of the estimated due date. A study of singleton live births came to the result that childbirth has a [[standard deviation]] of 14 days when gestational age is estimated by first trimester [[obstetric ultrasonography|ultrasound]], and 16 days when estimated directly by last menstrual period.<ref name=hoffman2008/>
<!-- ''The image below this hidden text has been approved by a majority of users after much discussion on the talk page. Please do not change or remove this picture without first discussing it in the talk page.'' -->


==Physiology==
[[Image:Pregnancy 26 weeks.jpg|thumb|right|A pregnant woman at 26 weeks.]]
===Capacity===
{{Further|Pregnancy over age 50}}


[[Fertility]] and [[fecundity]] are the respective capacities to [[Human fertilization|fertilize]] and establish a clinical pregnancy and have a live birth. [[Infertility]] is an impaired ability to establish a clinical pregnancy and [[Sterility (physiology)|sterility]] is the permanent inability to establish a clinical pregnancy.<ref name="Zegers-Hochschild Adamson Dyer Racowsky 2017 pp. 393–406">{{cite journal | vauthors = Zegers-Hochschild F, Adamson GD, Dyer S, Racowsky C, de Mouzon J, Sokol R, Rienzi L, Sunde A, Schmidt L, Cooke ID, Simpson JL, van der Poel S | title = The International Glossary on Infertility and Fertility Care, 2017 | journal = Fertility and Sterility | volume = 108 | issue = 3 | pages = 393–406 | date = September 2017 | pmid = 28760517 | doi = 10.1016/j.fertnstert.2017.06.005 | publisher = Elsevier BV | s2cid = 3640374 | doi-access = free }}</ref>
===Second trimester===
Months 4 through 6 of the pregnancy are called the second trimester. Most women feel more energized in this period, and begin to put on weight as the symptoms of morning sickness subside and eventually fade away. Although the [[fetus]] begins moving and takes a recognizable human shape during the first trimester, it is not until the second trimester that movement of the fetus, often referred to as "[[quickening]]", can be felt. This typically happens by the fourth month. The placenta is now fully functioning and the fetus is making insulin and urinating. The teeth are now formed inside the fetus' gums and the reproductive organs can be recognized, and can distinguish the fetus as male or female.


The capacity for pregnancy depends on the [[Human reproductive system|reproductive system]], [[Development of the reproductive system|its development]] and [[Variations in sex characteristics|its variation]], as well as on the condition of a person.
===Third trimester===
[[Women]] as well as [[intersex]] and [[transgender]] people who have a functioning [[female reproductive system]] are capable of pregnancy. In some cases, someone might be able to produce fertilizable eggs, but might not have a womb or none that can sufficiently gestate, in which case they might find [[surrogacy]].<ref name="nhs.uk 2021">{{Cite web |date=2021-11-18 |title=Differences in sex development |url=https://www.nhs.uk/conditions/differences-in-sex-development/ |access-date=2022-06-29 |website=nhs.uk}}</ref>
Final weight gain takes place, and the [[fetus]] begins to move regularly. The mother's [[belly button]] will sometimes "pop" out due to her growing [[belly]]. This period of her pregnancy can be uncomfortable, causing symptoms like weak bladder control and back-ache. Movement of the fetus becomes stronger and more frequent and the fetus prepares for viability outside the womb through improved brain, eye, and muscle function. The mother can feel the baby "rolling" and it may cause pain or discomfort when the baby is in the mother's ribs.


===Initiation===
It is during this time that a baby born [[Premature birth|prematurely]] may survive. The use of modern medical [[intensive care]] technology has greatly increased the probability of premature babies living, and has pushed back the boundary of viability to much earlier dates than would be possible without assistance. In spite of these developments, premature birth remains a major threat to the fetus, and may result in ill-health in later life, even if the baby survives.
{{See also|Human fertilization}}
<br clear="all" />
[[File:2904 Preembryonic Development-02.jpg|thumb|Fertilization and implantation in humans.]]


Through an interplay of hormones that includes [[follicle stimulating hormone]] that stimulates [[folliculogenesis]] and [[oogenesis]] creates a mature [[egg cell]], the female [[gamete]]. [[Human fertilization|Fertilization]] is the event where the egg cell fuses with the male gamete, [[spermatozoon]]. After the point of fertilization, the fused product of the female and male gamete is referred to as a [[zygote]] or fertilized egg. The fusion of female and male gametes usually occurs following the act of [[sexual intercourse]]. [[Pregnancy rate#Pregnancy rate for sexual intercourse|Pregnancy rates for sexual intercourse]] are highest during the [[menstrual cycle]] time from some 5 days before until 1 to 2 days after ovulation.<ref>{{Cite book | vauthors = Weschler T |url=https://archive.org/details/takingchargeofyo00toni |title=Taking Charge of Your Fertility |publisher=HarperCollins |year=2002 |isbn=978-0-06-093764-5 |edition=Revised |location=New York |pages=[https://archive.org/details/takingchargeofyo00toni/page/242 242], 374 |url-access=registration }}</ref> Fertilization can also occur by [[assisted reproductive technology]] such as [[artificial insemination]] and [[in vitro fertilisation]].
===Prenatal development and sonograph images===
{{seealso|Prenatal Development}}
Prenatal development is divided into two primary biological stages. The first is the [[embryo|embryonic stage]], which lasts for about two months. At this point, the [[fetus|fetal stage]] begins. At the beginning of the fetal stage, the risk of miscarriage decreases sharply,<ref> - [http://news.bbc.co.uk/2/hi/health/2176898.stm Q&A: Miscarriage]. (August 6 , 2002). ''BBC News.'' Retrieved [[2007-04-22]]: “The risk of miscarriage lessens as the pregnancy progresses. It decreases dramatically after the 8th week.”<br>
- [[Lennart Nilsson]], A Child is Born 91 (1990): at eight weeks, "the danger of a miscarriage . . . diminishes sharply."<br>
- “[http://www.womens-health.co.uk/miscarr.asp Women’s Health Information]”, Hearthstone Communications Limited: “The risk of miscarriage decreases dramatically after the 8th week as the weeks go by.” Retrieved [[2007-04-22]].</ref> all major structures including hands, feet, head, brain, and other organs are present, and they continue to grow and develop. When the fetal stage commences, a fetus is typically about 30 mm (1.2 inches) in length, and the heart can be seen beating via sonograph; the fetus bends the head, and also makes general movements and startles that involve the whole body. Brain stem activity has been detected 54 days after conception. Some fingerprint formation occurs from the beginning of the fetal stage.


Fertilization (conception) is sometimes used as the initiation of pregnancy, with the derived age being termed [[fertilization age]]. Fertilization usually occurs about two weeks before the ''next'' expected menstrual period.
<gallery>
Image:Month 1.svg|Relative size in 1st Month (simplified illustration)
Image:Month 3.svg|Relative size in 3rd Month (simplified illustration)
Image:Month 5.svg|Relative size in 5th Month (simplified illustration)
Image:Month 9.svg|Relative size in 9th Month (simplified illustration)
</gallery>


A third point in time is also considered by some people to be the true beginning of a pregnancy: This is time of implantation, when the future fetus attaches to the lining of the uterus. This is about a week to ten days after fertilization.<ref name="Berger">{{Cite book | vauthors = Berger KS |url= https://books.google.com/books?id=mC_LNMy2rbkC |title=The Developing Person Through the Life Span |publisher=Macmillan |year=2011 |isbn=978-1-4292-3205-0 |page=90 |archive-url=https://web.archive.org/web/20160425172707/https://books.google.com/books?id=mC_LNMy2rbkC |archive-date=25 April 2016 |url-status=live }}</ref>
<gallery>

Image:Scan07semanas.png|7 weeks
===Development of embryo and fetus===
Image:Scan13semanas1.png|13 weeks
{{Main|Human embryonic development||Prenatal development|Fetus}}
Image:Scan17semanas2.png|17 weeks
[[File:HumanEmbryogenesis.svg|thumb|The initial stages of [[human embryogenesis]]]]
Image:Scan20semanas1.png|20 weeks
The sperm and the egg cell, which has been released from one of the female's two [[ovaries]], unite in one of the two [[fallopian tube]]s. The fertilized egg, known as a [[zygote]], then moves toward the uterus, a journey that can take up to a week to complete. Cell division begins approximately 24 to 36 hours after the female and male cells unite. Cell division continues at a rapid rate and the cells then develop into what is known as a [[blastocyst]]. The blastocyst arrives at the uterus and attaches to the uterine wall, a process known as [[implantation (human embryo)|implantation]].

The development of the mass of cells that will become the infant is called [[Human embryogenesis|embryogenesis]] during the first approximately ten weeks of gestation. During this time, cells begin to differentiate into the various body systems. The basic outlines of the organ, body, and nervous systems are established. By the end of the embryonic stage, the beginnings of features such as fingers, eyes, mouth, and ears become visible. Also during this time, there is development of structures important to the support of the embryo, including the [[placenta]] and [[umbilical cord]]. The placenta connects the developing embryo to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. The umbilical cord is the connecting cord from the embryo or fetus to the placenta.

After about ten weeks of gestational age—which is the same as eight weeks after conception—the embryo becomes known as a [[fetus]].<ref name="MSD">{{Cite web |title=Stages of Development of the Fetus – Women's Health Issues |url=https://www.msdmanuals.com/en-gb/home/women-s-health-issues/normal-pregnancy/stages-of-development-of-the-fetus |access-date=10 July 2020 |website=MSD Manual Consumer Version}}</ref> At the beginning of the fetal stage, the risk of miscarriage decreases sharply.<ref name=sharply>
* [[Lennart Nilsson]], [[A Child Is Born (book)|A Child is Born]] 91 (1990): at eight weeks, "the danger of a miscarriage ... diminishes sharply."
* "[http://www.womens-health.co.uk/miscarr.asp Women's Health Information] {{webarchive|url=https://web.archive.org/web/20070430200911/http://www.womens-health.co.uk/miscarr.asp |date=30 April 2007 }}", Hearthstone Communications Limited: "The risk of miscarriage decreases dramatically after the 8th week as the weeks go by." Retrieved 2007-04-22.</ref> At this stage, a fetus is about {{Convert|30|mm|1|abbr=in}} in length, the heartbeat is seen via ultrasound, and the fetus makes involuntary motions.<ref name="Prechtl">{{Cite book | vauthors = Kalverboer AF, Gramsbergen AA |url= https://books.google.com/books?id=FzyPozUyKPkC&pg=RA1-PA416 |title=Handbook of Brain and Behaviour in Human Development |date=1 January 2001 |publisher=Springer |isbn=978-0-7923-6943-1 |page=1 |archive-url=https://web.archive.org/web/20150919073812/https://books.google.com/books?id=FzyPozUyKPkC&pg=RA1-PA416 |archive-date=19 September 2015 |url-status=live }}</ref> During continued fetal development, the early body systems, and structures that were established in the embryonic stage continue to develop. Sex organs begin to appear during the third month of gestation. The fetus continues to grow in both weight and length, although the majority of the physical growth occurs in the last weeks of pregnancy.

Electrical [[brain activity]] is first detected at the end of week 5 of gestation, but as in [[brain-death|brain-dead]] patients, it is primitive neural activity rather than the beginning of conscious brain activity. Synapses do not begin to form until week 17.<ref>{{Cite book |url=https://books.google.com/books?id=m7USFu5Z0lQC&pg=PA142 |title=Neuroethics: defining the issues in theory, practice, and policy |publisher=Oxford University Press |year=2008 |isbn=978-0-19-856721-9 | veditors = Illes J |edition=Repr. |location=Oxford |pages=142 |archive-url=https://web.archive.org/web/20150919015206/https://books.google.com/books?id=m7USFu5Z0lQC&pg=PA142 |archive-date=19 September 2015 |url-status=live }}</ref> Neural connections between the [[sensory cortex]] and [[thalamus]] develop as early as 24 weeks' gestational age, but the first evidence of their function does not occur until around 30 weeks, when minimal [[consciousness]], [[dream]]ing, and the ability to feel pain emerges.<ref>
*{{Cite book | vauthors = Harley TA |url= https://books.google.com/books?id=3DcTEAAAQBAJ |title=The Science of Consciousness: Waking, Sleeping and Dreaming |date=2021 |publisher=Cambridge University Press |isbn=978-1-107-12528-5 |location=Cambridge, United Kingdom |page=245 |access-date=May 3, 2022}}
* {{cite book | veditors = Cleeremans A, Wilken P, Bayne T |title=The Oxford Companion to Consciousness |date=2009 |publisher=Oxford University Press |location=New York, NY |isbn=978-0-19-856951-0 |page=229 |url=https://books.google.com/books?id=DuTnCwAAQBAJ |access-date=May 3, 2022}}
* {{cite book | veditors = Thompson E, Moscovitch M, Zelazo PD |title=The Cambridge Handbook of Consciousness |date=2007 |publisher=Cambridge University Press |location=Cambridge, United Kingdom |isbn=978-1-139-46406-2 |pages=415–417 |url=https://books.google.com/books?id=o9ZRc6-FDg8C |access-date=May 3, 2022}}</ref>

Although the fetus begins to move during the first trimester, it is not until the second trimester that movement, known as [[quickening]], can be felt. This typically happens in the fourth month, more specifically in the 20th to 21st week, or by the 19th week if the woman has been pregnant before. It is common for some women not to feel the fetus move until much later. During the second trimester, when the body size changes, [[maternity clothes]] may be worn.

<gallery class="center">
File:6 weeks pregnant.png|Embryo at 4 weeks after fertilization (gestational age of 6 weeks)
File:10 weeks pregnant.png|Fetus at 8 weeks after fertilization (gestational age of 10 weeks)
File:20 weeks pregnant.png|Fetus at 18 weeks after fertilization (gestational age of 20 weeks)
File:40 weeks pregnant.png|Fetus at 38 weeks after fertilization (gestational age of 40 weeks)
</gallery>
</gallery>
<gallery class="center">
File:Month 1.svg|Relative size in 1st month (simplified illustration)
File:Month 3.svg|Relative size in 3rd month (simplified illustration)
File:Month 5.svg|Relative size in 5th month (simplified illustration)
File:Month 9.svg|Relative size in 9th month (simplified illustration)
</gallery>

===Maternal changes===
[[Image:Bumm 123 lg.jpg|thumb|The [[uterus]] expands making up a larger and larger portion of the abdomen. During the final stages of gestation the uterus may drop to a lower position.]]

{{Main|Maternal physiological changes in pregnancy}}
[[File:Breast changes during pregnancy 1.png|thumb|Breast changes as seen during pregnancy. The areolae are larger and darker.]]
During pregnancy, a woman undergoes many normal [[physiological]] changes, including [[Parental brain|behavioral]], [[cardiovascular]], [[hematologic]], [[metabolic]], [[renal]], and [[respiration (physiology)|respiratory]] changes. Increases in [[Blood sugar level|blood sugar]], [[respiratory rate|breathing]], and [[cardiac output]] are all required. Levels of [[progesterone]] and [[estrogen]]s rise continually throughout pregnancy, suppressing the [[Hypothalamic–pituitary–gonadal axis|hypothalamic axis]] and therefore the [[menstrual cycle]]. A full-term pregnancy at an early age (less than 25 years) reduces the risk of [[breast cancer|breast]], [[ovarian cancer|ovarian]], and [[endometrial cancer]], and the risk declines further with each additional full-term pregnancy.<ref>{{Cite web |title=Abortion & Pregnancy Risks |url=http://ldh.la.gov/index.cfm/page/915 |access-date=22 August 2019 |publisher=[[Louisiana Department of Health]]}}</ref><ref>{{Cite web |date=30 November 2016 |title=Reproductive History and Cancer Risk |url=https://www.cancer.gov/about-cancer/causes-prevention/risk/hormones/reproductive-history-fact-sheet#are-any-pregnancy-related-factors-associated-with-a-lower-risk-of-breast-cancer |access-date=23 August 2019 |website=National Cancer Institute}}</ref>
[[File:Pregnancy 26 weeks 1.jpg|upright|thumb|End of second trimester + 2 weeks (26 weeks of pregnancy)]]
The fetus is [[genetics|genetically]] different from its mother and can therefore be viewed as an unusually successful [[allograft]].<ref name="Mor">{{Cite book |title=Immunology of pregnancy |date=2006 |publisher=Landes Bioscience/Eurekah.com; Springer Science+Business Media |isbn=978-0-387-34944-2 | veditors = Mor G |series=Medical intelligence unit |location=Georgetown, Tex. : New York |pages=1–4 |doi=10.1007/0-387-34944-8 }}</ref> The main reason for this success is increased [[Immune tolerance in pregnancy|immune tolerance]] during pregnancy,<ref>{{cite journal | vauthors = Williams Z | title = Inducing tolerance to pregnancy | journal = The New England Journal of Medicine | volume = 367 | issue = 12 | pages = 1159–1161 | date = September 2012 | pmid = 22992082 | pmc = 3644969 | doi = 10.1056/NEJMcibr1207279 }}</ref> which prevents the mother's body from mounting an [[immune response|immune system response]] against certain triggers.<ref name="Mor" />

During the first trimester, [[minute ventilation]] increases by 40 percent.<ref name="pmid11316633">{{cite journal | vauthors = Campbell LA, Klocke RA | title = Implications for the pregnant patient | journal = American Journal of Respiratory and Critical Care Medicine | volume = 163 | issue = 5 | pages = 1051–1054 | date = April 2001 | pmid = 11316633 | doi = 10.1164/ajrccm.163.5.16353 }}</ref> The womb will grow to the size of a [[lemon]] by eight weeks. Many [[symptoms and discomforts of pregnancy]], such as nausea and [[breast tenderness|tender breasts]], appear in the first trimester.<ref>{{Cite web |date=2017-12-20 |title=Your baby at 0–8 weeks pregnancy – Pregnancy and baby guide – NHS Choices |url=http://www.nhs.uk/conditions/pregnancy-and-baby/pages/pregnancy-weeks-4-5-6-7-8.aspx#close |url-status=live |archive-url=https://web.archive.org/web/20131120025033/http://www.nhs.uk/conditions/pregnancy-and-baby/pages/pregnancy-weeks-4-5-6-7-8.aspx#close |archive-date=20 November 2013 |website=nhs.uk }}</ref>

During the second trimester, most women feel more energized and put on weight as the symptoms of [[morning sickness]] subside. They begin to feel regular [[fetal movement]]s, which can become strong and even disruptive.{{citation needed|date=May 2023}}

[[Braxton Hicks contractions]] are sporadic [[uterine contraction]]s that may start around six weeks into a pregnancy; however, they are usually not felt until the second or third trimester.<ref name="Hen2005">{{Cite book | vauthors = Hennen L, Murray L, Scott J |url=https://books.google.com/books?id=AK60Xmnrm_AC&q=%22Braxton+Hicks+contractions%22&pg=PA294 |title=The BabyCenter Essential Guide to Pregnancy and Birth: Expert Advice and Real-World Wisdom from THE tip Top Pregnancy and Parenting Resource |publisher=Rodale Books |year=2005 |isbn=1-59486-211-7 |location=Emmaus, Penn.}}</ref>

Final weight gain takes place during the third trimester; this is the most weight gain throughout the pregnancy. The woman's abdomen will transform in shape as the fetus turns in a downward position ready for birth. The woman's [[navel]] will sometimes become convex, "popping" out, due to the expanding [[abdomen]]. The uterus, the muscular organ that holds the developing fetus, can expand up to 20 times its normal size during pregnancy.

[[Head engagement]], also called "lightening" or "dropping", occurs as the fetal head descends into a [[cephalic presentation]]. While it relieves pressure on the upper abdomen and gives a renewed ease in breathing, it also severely reduces bladder capacity, resulting in a need to [[urinary frequency|void more frequently]], and increases pressure on the pelvic floor and the rectum. It is not possible to predict when lightening will occur. In a first pregnancy it may happen a few weeks before the due date, though it may happen later or even not until labor begins, as is typical with subsequent pregnancies.<ref>{{Cite web |title=Pregnancy: Dropping (Lightening) |url=https://www.uofmhealth.org/health-library/aa88159#:~:text=At%20the%20end%20of%20the,but%20it%20can%20happen%20earlier. |access-date=June 9, 2021 |website=University of Michigan}}</ref>

It is during the third trimester that maternal activity and sleep positions may affect [[fetal development]] due to restricted [[blood flow]]. For instance, the enlarged uterus may impede blood flow by compressing the [[vena cava]] when lying flat, a condition that can be relieved by lying on the left side.<ref name="pmid21673002">{{cite journal | vauthors = Stacey T, Thompson JM, Mitchell EA, Ekeroma AJ, Zuccollo JM, McCowan LM | title = Association between maternal sleep practices and risk of late stillbirth: a case-control study | journal = BMJ | volume = 342 | pages = d3403 | date = June 2011 | pmid = 21673002 | pmc = 3114953 | doi = 10.1136/bmj.d3403 }}</ref>

===Childbirth===
{{Main|Childbirth}}
Childbirth, referred to as labor and delivery in the medical field, is the process whereby an infant is born.<ref name="Williams" />

A woman is considered to be in labor when she begins experiencing regular uterine contractions, accompanied by changes of her cervix—primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labors, while others find that concentrating on the birth helps to quicken labor and lessen the sensations. Most births are successful vaginal births, but sometimes complications arise and a woman may undergo a [[cesarean section]].

During the time immediately after birth, both the mother and the [[baby]] are hormonally cued to bond, the mother through the release of [[oxytocin]], a hormone also released during [[breastfeeding]]. Studies show that skin-to-skin contact between a mother and her newborn immediately after birth is beneficial for both the mother and baby. A review done by the [[World Health Organization]] found that skin-to-skin contact between mothers and babies after birth reduces crying, improves mother–infant interaction, and helps mothers to breastfeed successfully. They recommend that [[neonates]] be allowed to bond with the mother during their first two hours after birth, the period that they tend to be more alert than in the following hours of early life.<ref>{{cite web|url=http://apps.who.int/rhl/newborn/gpcom/en/index.html|title=RHL|website=apps.who.int|archive-url=https://web.archive.org/web/20111227074038/http://apps.who.int/rhl/newborn/gpcom/en/index.html|archive-date=27 December 2011}}</ref>

====Childbirth maturity stages====
{{Further|Preterm birth|Postterm pregnancy}}
{{anchor|Term}}
{| class="wikitable floatright"
|+Stages of pregnancy term
|-
! stage !! starts !! ends
|-
| Preterm<ref name="preterm definition">{{Cite web |last=World Health Organization |date=November 2013 |title=Preterm birth |url=https://www.who.int/mediacentre/factsheets/fs363/en/ |url-status=live |archive-url=https://web.archive.org/web/20140907152746/http://www.who.int/mediacentre/factsheets/fs363/en/ |archive-date=7 September 2014 |access-date=19 September 2014 |website=who.int }}</ref>||style="text-align: center;"|- || at 37 weeks
|-
| Early term<ref name="term definition">{{Cite web |last1=American Congress of Obstetricians and Gynecologists |author-link=American Congress of Obstetricians and Gynecologists |last2=Society for Maternal-Fetal Medicine |author-link2=Society for Maternal-Fetal Medicine |date=22 October 2013 |title=Ob-Gyns Redefine Meaning of 'Term Pregnancy' |url=http://www.acog.org/About-ACOG/News-Room/News-Releases/2013/Ob-Gyns-Redefine-Meaning-of-Term-Pregnancy |archive-url=https://web.archive.org/web/20140915035035/http://www.acog.org/About-ACOG/News-Room/News-Releases/2013/Ob-Gyns-Redefine-Meaning-of-Term-Pregnancy |archive-date=15 September 2014 |access-date=19 September 2014 |website=acog.org }}</ref> || 37 weeks || 39 weeks
|-
| Full term<ref name="term definition" /> || 39 weeks || 41 weeks
|-
| Late term<ref name="term definition" /> || 41 weeks || 42 weeks
|-
| Postterm<ref name="term definition" /> || 42 weeks ||style="text-align: center;"|-
|-
|}
In the ideal [[childbirth]], labor begins on its own when a woman is "at term".<ref name="ACOGfive-2"/>
Events before completion of 37 weeks are considered preterm.<ref name="preterm definition" /> [[Preterm birth]] is associated with a range of complications and should be avoided if possible.<ref name="SaigalDoyle2008">{{cite journal | vauthors = Saigal S, Doyle LW | title = An overview of mortality and sequelae of preterm birth from infancy to adulthood | journal = Lancet | volume = 371 | issue = 9608 | pages = 261–269 | date = January 2008 | pmid = 18207020 | doi = 10.1016/S0140-6736(08)60136-1 | s2cid = 17256481 }}</ref>

Sometimes if a woman's [[Rupture of membranes|water breaks]] or she has [[Uterine contraction|contractions]] before 39 weeks, birth is unavoidable.<ref name="term definition" /> However, spontaneous birth after 37 weeks is considered term and is not associated with the same risks of a preterm birth.<ref name="Williams">{{Cite book |chapter=Chapter 12. Teratology, Teratogens, and Fetotoxic Agents |chapter-url=http://ucsfcat.library.ucsf.edu/record=b2124757~S0 |veditors=Cunningham FG, Leveno KJ, Bloom SL, Spong CY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS |title=William's Obstetrics |date=2014 |publisher=McGraw-Hill Education |isbn=978-0-07-179893-8 |access-date=9 November 2015 |archive-date=31 December 2018 |archive-url=https://web.archive.org/web/20181231154352/http://ucsfcat.library.ucsf.edu/record=b2124757~S0 }}</ref> Planned birth before 39 weeks by [[caesarean section]] or [[labor induction]], although "at term", results in an increased risk of complications.<ref name="ACOGfive-1">{{Citation |last=American Congress of Obstetricians and Gynecologists |title=Five Things Physicians and Patients Should Question |date=February 2013 |url=http://www.choosingwisely.org/doctor-patient-lists/american-college-of-obstetricians-and-gynecologists/ |work=[[Choosing Wisely]]: an initiative of the [[ABIM Foundation]] |archive-url=https://web.archive.org/web/20130901094916/http://www.choosingwisely.org/doctor-patient-lists/american-college-of-obstetricians-and-gynecologists/ |publisher=[[American Congress of Obstetricians and Gynecologists]] |access-date=1 August 2013 |archive-date=1 September 2013 |author-link=American Congress of Obstetricians and Gynecologists |url-status=live}}, which cites
* {{Citation | vauthors = Main E, Oshiro B, Chagolla B, Bingham D, Dang-Kilduff L, Kowalewski L |title=Elimination of Non-medically Indicated (Elective) Deliveries Before 39 Weeks Gestational Age |publisher=[[March of Dimes]]; California Maternal Quality Care Collaborative; Maternal, Child and Adolescent Health Division; Center for Family Health; [[California Department of Public Health]] |url=http://www.cdph.ca.gov/programs/mcah/Documents/MCAH-EliminationOfNon-MedicallyIndicatedDeliveries.pdf |access-date=1 August 2013 |archive-url=https://web.archive.org/web/20121110174951/http://www.cdph.ca.gov/programs/mcah/Documents/MCAH-EliminationOfNon-MedicallyIndicatedDeliveries.pdf |archive-date=10 November 2012 }}</ref> This is from factors including [[Transient tachypnea of the newborn|underdeveloped lungs of newborns]], infection due to underdeveloped immune system, feeding problems due to underdeveloped brain, and [[jaundice]] from underdeveloped liver.<ref name="npr July 2011">{{cite web |url=https://www.npr.org/templates/transcript/transcript.php?storyId=138473097 |title=Doctors To Pregnant Women: Wait at Least 39 Weeks |work=[[All Things Considered]] |author=Michele Norris |author-link=Michele Norris |access-date=20 August 2011 |date=18 July 2011 |url-status=live |archive-url=https://web.archive.org/web/20110723081827/http://www.npr.org/templates/transcript/transcript.php?storyId=138473097 |archive-date=23 July 2011 }}</ref>

Babies born between 39 and 41 weeks' gestation have better outcomes than babies born either before or after this range.<ref name="term definition" /> This special time period is called "full term".<ref name="term definition" /> Whenever possible, waiting for labor to begin on its own in this time period is best for the health of the mother and baby.<ref name="ACOGfive-2" /> The decision to perform an induction must be made after weighing the risks and benefits, but is safer after 39 weeks.<ref name="ACOGfive-2" />

Events after 42 weeks are considered [[Postterm pregnancy|postterm]].<ref name="term definition" /> When a pregnancy exceeds 42 weeks, the risk of complications for both the woman and the fetus increases significantly.<ref name="UpToDate">{{Cite web | vauthors = Norwitz ER |title=Postterm Pregnancy (Beyond the Basics) |url=http://www.uptodate.com/contents/postterm-pregnancy-beyond-the-basics |url-status=live |archive-url=https://web.archive.org/web/20121007020439/http://www.uptodate.com/contents/postterm-pregnancy-beyond-the-basics |archive-date=7 October 2012 |access-date=24 August 2012 |publisher=UpToDate, Inc. }}</ref><ref>{{Cite web |last=The American College of Obstetricians and Gynecologists |date=April 2006 |title=What To Expect After Your Due Date |url=http://www.medem.com/MedLB/article_detaillb.cfm?article_ID=ZZZRDLPH97C&sub_cat=2005 |archive-url=https://web.archive.org/web/20030429020622/http://www.medem.com/medlb/article_detaillb.cfm?article_ID=ZZZRDLPH97C&sub_cat=2005 |archive-date=2003-04-29 |access-date=16 January 2008 |website=Medem |publisher=Medem, Inc.}}</ref> Therefore, in an otherwise uncomplicated pregnancy, obstetricians usually prefer to induce labor at some stage between 41 and 42 weeks.<ref>{{Cite web |year=2001 |title=Induction of labour – Evidence-based Clinical Guideline Number 9 |url=http://www.rcog.org.uk/resources/public/pdf/rcog_induction_of_labour.pdf |archive-url=https://web.archive.org/web/20061230063449/http://www.rcog.org.uk/resources/public/pdf/rcog_induction_of_labour.pdf |archive-date=30 December 2006 |access-date=18 January 2008 |publisher=Royal College of Obstetricians and Gynaecologists}}</ref>

===Postnatal period===
{{Main|Postpartum period}}
The [[postpartum period]] also referred to as the ''puerperium'', is the postnatal period that begins immediately after delivery and extends for about six weeks.<ref name="Williams" /> During this period, the mother's body begins the return to pre-pregnancy conditions that includes changes in hormone levels and uterus size.<ref name="Williams" />

==Diagnosis==
The beginning of pregnancy may be detected either based on symptoms by the woman herself, or by using [[pregnancy test]]s. However, an important condition with serious health implications that is quite common is the [[denial of pregnancy]] by the pregnant woman. About 1 in 475 denials will last until around the 20th week of pregnancy. The proportion of cases of denial, persisting until delivery is about 1 in 2500.<ref name="pmid21725094">{{cite journal | vauthors = Jenkins A, Millar S, Robins J | title = Denial of pregnancy: a literature review and discussion of ethical and legal issues | journal = Journal of the Royal Society of Medicine | volume = 104 | issue = 7 | pages = 286–291 | date = July 2011 | pmid = 21725094 | pmc = 3128877 | doi = 10.1258/jrsm.2011.100376 }}</ref> Conversely, some non-pregnant women have a very strong belief that they are pregnant along with some of the physical changes. This condition is known as a [[false pregnancy]].<ref name="Gabbe2012">{{Cite book | vauthors = Gabbe S |title=Obstetrics: normal and problem pregnancies |date=2012-01-01 |publisher=Elsevier/Saunders |isbn=978-1-4377-1935-2 |edition=6th |location=Philadelphia |page=[https://books.google.com/books?id=-3ufSTqeb6cC&pg=PA1184 1184] }}</ref>

===Physical signs===
{{Further|Signs and symptoms of pregnancy}}
[[File:Linea nigra.jpg|thumb|[[Linea nigra]] in a woman at 22 weeks pregnant]]
Most pregnant women experience a number of symptoms,<ref name="pregnancy symptoms">{{Cite web |date=11 March 2010 |title=Pregnancy Symptoms |url=http://www.nhs.uk/livewell/sexandyoungpeople/pages/amipregnant.aspx |url-status=live |archive-url=https://web.archive.org/web/20100228005252/http://www.nhs.uk/Livewell/Sexandyoungpeople/Pages/AmIpregnant.aspx |archive-date=28 February 2010 |access-date=11 March 2010 |publisher=[[National Health Service (NHS)]] }}</ref> which can signify pregnancy. A number of early [[medical sign]]s are associated with pregnancy.<ref name="mayo symptoms">{{Cite web |date=22 February 2007 |title=Early symptoms of pregnancy: What happens right away |url=http://www.mayoclinic.com/health/symptoms-of-pregnancy/PR00102 |url-status=live |archive-url=https://web.archive.org/web/20070914132824/http://www.mayoclinic.com/health/symptoms-of-pregnancy/PR00102 |archive-date=14 September 2007 |access-date=22 August 2007 |publisher=[[Mayo Clinic]] }}</ref><ref name="American Pregnancy Association">{{Cite web |title=Pregnancy Symptoms – Early Signs of Pregnancy: American Pregnancy Association |url=http://www.americanpregnancy.org/gettingpregnant/earlypregnancysymptoms.html |url-status=live |archive-url=https://web.archive.org/web/20080115221928/http://www.americanpregnancy.org/gettingpregnant/earlypregnancysymptoms.html |archive-date=15 January 2008 |access-date=16 January 2008 }}</ref> These signs include:
* the presence of [[human chorionic gonadotropin]] (hCG) in the blood and urine
* missed [[menstrual cycle|menstrual period]]
* [[implantation bleeding]] that occurs at [[Implantation (embryology)|implantation]] of the embryo in the uterus during the third or fourth week after last menstrual period
* increased [[basal body temperature]] sustained for over two weeks after [[ovulation]]
* [[Chadwick's sign]] (bluish discolouration of the [[cervix]], [[Human vagina|vagina]], and [[Human vulva|vulva]])
* [[Goodell's sign]] (softening of the vaginal portion of the cervix)
* [[Hegar's sign]] (softening of the [[uterine isthmus]])
* [[Hyperpigmentation|Pigmentation]] of the [[linea alba (abdomen)|linea alba]], called [[linea nigra]] (darkening of the skin in a midline of the [[abdomen]], resulting from hormonal changes, usually appearing around the middle of pregnancy).<ref name="mayo symptoms" /><ref name="American Pregnancy Association" />
* Darkening of the nipples and areolas due to an increase in hormones.<ref name="pregnancy video">{{Cite web |year=2008 |title=Pregnancy video |url=http://sexperienceuk.channel4.com/education/about/pregnancy |url-status=live |archive-url=https://web.archive.org/web/20090123143201/http://sexperienceuk.channel4.com/education/about/pregnancy |archive-date=23 January 2009 |access-date=22 January 2009 |publisher=Channel 4 }}</ref>

===Biomarkers===
{{Further|Pregnancy test}}
Pregnancy detection can be accomplished using one or more various [[pregnancy test]]s,<ref name="pregnancy">{{Cite web |date=19 March 2010 |title=NHS Pregnancy Planner |url=http://www.nhs.uk/Planners/Pregnancycareplanner |access-date=19 March 2010 |publisher=[[National Health Service (NHS)]] |archive-date=29 August 2021 |archive-url=https://web.archive.org/web/20210829003934/https://www.nhs.uk/pregnancy/ |url-status=dead }}</ref> which detect hormones generated by the newly formed [[placenta]], serving as [[Biomarker (medicine)|biomarkers]] of pregnancy.<ref>{{Cite book |url=http://ucsfcat.library.ucsf.edu/record=b2263261~S0 |title=Human chorionic gonadotropin (hCG) |date=2015 |publisher=Elsevier |isbn=978-0-12-800821-8 |veditors=Cole LA, Butler SA |edition=2nd |location=Amsterdam |access-date=10 November 2015 |archive-date=26 January 2021 |archive-url=https://web.archive.org/web/20210126052510/http://ucsfcat.library.ucsf.edu/record=b2263261~S0 }}</ref> Blood and urine tests can detect pregnancy by 11 and 14 days, respectively, after fertilization.<ref>{{cite journal | vauthors = Qasim SM, Callan C, Choe JK | title = The predictive value of an initial serum beta human chorionic gonadotropin level for pregnancy outcome following in vitro fertilization | journal = Journal of Assisted Reproduction and Genetics | volume = 13 | issue = 9 | pages = 705–708 | date = October 1996 | pmid = 8947817 | doi = 10.1007/BF02066422 | s2cid = 36218409 }}</ref><ref name="American Pregnancy Association_2021">{{Cite web |date=2021-10-18 |title=What is HCG? |url=https://americanpregnancy.org/getting-pregnant/hcg-levels/ |access-date=2023-07-23 |website=American Pregnancy Association}}</ref> Blood pregnancy tests are more [[Sensitivity and specificity|sensitive]] than urine tests (giving fewer false negatives).<ref>{{Cite web |title=BestBets: Serum or Urine beta-hCG? |url=http://www.bestbets.org/bets/bet.php?id=936 |url-status=live |archive-url=https://web.archive.org/web/20081231135953/http://www.bestbets.org/bets/bet.php?id=936 |archive-date=31 December 2008 }}</ref> Home pregnancy tests are urine tests, and normally detect a pregnancy 12 to 15 days after fertilization.<ref name="Cole">{{cite journal | vauthors = Cole LA, Khanlian SA, Sutton JM, Davies S, Rayburn WF | title = Accuracy of home pregnancy tests at the time of missed menses | journal = American Journal of Obstetrics and Gynecology | volume = 190 | issue = 1 | pages = 100–105 | date = January 2004 | pmid = 14749643 | doi = 10.1016/j.ajog.2003.08.043 }}</ref> A quantitative blood test can determine approximately the date the embryo was fertilized because [[Human chorionic gonadotropin|hCG]] levels double every 36 to 72 hours before 8 weeks' gestation.<ref name="Williams" /><ref name="American Pregnancy Association_2021" /> A single test of [[progesterone]] levels can also help determine how likely a fetus will survive in those with a [[threatened miscarriage]] (bleeding in early pregnancy), but only if the ultrasound result was inconclusive.<ref name="pmid23045257">{{cite journal | vauthors = Verhaegen J, Gallos ID, van Mello NM, Abdel-Aziz M, Takwoingi Y, Harb H, Deeks JJ, Mol BW, Coomarasamy A | title = Accuracy of single progesterone test to predict early pregnancy outcome in women with pain or bleeding: meta-analysis of cohort studies | journal = BMJ | volume = 345 | pages = e6077 | date = September 2012 | pmid = 23045257 | pmc = 3460254 | doi = 10.1136/bmj.e6077 }}</ref>

===Ultrasound===
{{Main|Obstetric ultrasonography}}
[[Obstetric ultrasonography]] can detect [[List of fetal abnormalities|fetal abnormalities]], detect [[multiple pregnancy|multiple pregnancies]], and improve gestational dating at 24 weeks.<ref>{{cite journal | vauthors = Whitworth M, Bricker L, Mullan C | title = Ultrasound for fetal assessment in early pregnancy | journal = The Cochrane Database of Systematic Reviews | volume = 2015 | issue = 7 | pages = CD007058 | date = July 2015 | pmid = 26171896 | pmc = 4084925 | doi = 10.1002/14651858.CD007058.pub3 }}</ref> The resultant estimated [[Gestational age (obstetrics)|gestational age]] and due date of the fetus are slightly more accurate than methods based on last menstrual period.<ref>{{cite journal | vauthors = Nguyen TH, Larsen T, Engholm G, Møller H | title = Evaluation of ultrasound-estimated date of delivery in 17,450 spontaneous singleton births: do we need to modify Naegele's rule? | journal = Ultrasound in Obstetrics & Gynecology | volume = 14 | issue = 1 | pages = 23–28 | date = July 1999 | pmid = 10461334 | doi = 10.1046/j.1469-0705.1999.14010023.x | s2cid = 30749264 | doi-access = free }}</ref> Ultrasound is used to measure the [[Nuchal scan|nuchal fold]] in order to screen for [[Down syndrome]].<ref>{{Cite book |title=Current Medical Diagnosis & Treatment 2015 |vauthors=Pyeritz RE |publisher=McGraw-Hill |year=2014}}</ref>

==Management==
[[File:Lifting guidelines during pregnancy - NIOSH.jpg|thumb|upright=1.3|Flowchart showing the recommended weight limits for lifting at work during pregnancy as a function of lifting frequency, weeks of gestation, and the position of the lifted object relative to the lifter's body.<ref>{{cite journal | vauthors = Waters TR, MacDonald LA, Hudock SD, Goddard DE | title = Provisional recommended weight limits for manual lifting during pregnancy | journal = Human Factors | volume = 56 | issue = 1 | pages = 203–214 | date = February 2014 | pmid = 24669554 | pmc = 4606868 | doi = 10.1177/0018720813502223 | url = https://www.cdc.gov/niosh/nioshtic-2/20043108.html | url-status = live | archive-url = https://web.archive.org/web/20170401144543/https://www.cdc.gov/niosh/nioshtic-2/20043108.html | archive-date = 1 April 2017 }}</ref><ref name="MacDonaldWaters2013">{{cite journal | vauthors = MacDonald LA, Waters TR, Napolitano PG, Goddard DE, Ryan MA, Nielsen P, Hudock SD | title = Clinical guidelines for occupational lifting in pregnancy: evidence summary and provisional recommendations | journal = American Journal of Obstetrics and Gynecology | volume = 209 | issue = 2 | pages = 80–88 | date = August 2013 | pmid = 23467051 | pmc = 4552317 | doi = 10.1016/j.ajog.2013.02.047 }}</ref>
|alt=An infographic showing a flow chart leading to three diagrams, each showing two human figures depicting different lengths of gestation, with a grid showing weight limits for different locations in front of the body|250x250px]]

===Prenatal care===
{{Main|Prenatal care|pre-conception counseling}}
[[Pre-conception counseling]] is care that is provided to a woman or couple to discuss conception, pregnancy, current health issues and recommendations for the period before pregnancy.<ref name="Lyons">{{Cite book |vauthors=Lyons P |url=http://ucsfcat.library.ucsf.edu/record=b2282976~S0 |title=Obstetrics in family medicine: a practical guide |date=2015 |publisher=Humana Press |isbn=978-3-319-20077-4 |edition=2nd |series=Current clinical practice |location=Cham, Switzerland |pages=19–28 |access-date=11 November 2015 |archive-date=26 January 2021 |archive-url=https://web.archive.org/web/20210126165622/http://ucsfcat.library.ucsf.edu/record=b2282976~S0 }}</ref>

[[Prenatal care|Prenatal medical care]] is the medical and nursing care recommended for women during pregnancy, time intervals and exact goals of each visit differ by country.<ref>{{cite web|title=WHO {{!}} Antenatal care |url=https://www.who.int/gho/maternal_health/reproductive_health/antenatal_care_text/en/ |website=www.who.int |access-date=2015-11-10 |archive-url=https://web.archive.org/web/20151120203220/http://www.who.int/gho/maternal_health/reproductive_health/antenatal_care_text/en/ |archive-date=20 November 2015 }}</ref> Women who are high risk have better outcomes if they are seen regularly and frequently by a medical professional than women who are low risk.<ref>{{cite journal | vauthors = Dowswell T, Carroli G, Duley L, Gates S, Gülmezoglu AM, Khan-Neelofur D, Piaggio G | title = Alternative versus standard packages of antenatal care for low-risk pregnancy | journal = The Cochrane Database of Systematic Reviews | volume = 2015 | issue = 7 | pages = CD000934 | date = July 2015 | pmid = 26184394 | pmc = 7061257 | doi = 10.1002/14651858.cd000934.pub3 | collaboration = American College of Obstetricians Gynecologists Committee on Health Care for Undeserved Women }}</ref> A woman can be labeled as high risk for different reasons including previous complications in pregnancy, complications in the current pregnancy, current medical diseases, or social issues.<ref>{{cite journal | title = ACOG Committee Opinion No. 343: psychosocial risk factors: perinatal screening and intervention | journal = Obstetrics and Gynecology | volume = 108 | issue = 2 | pages = 469–477 | date = August 2006 | pmid = 16880322 | doi = 10.1097/00006250-200608000-00046 | author1 = American College of Obstetricians Gynecologists Committee on Health Care for Undeserved Women | doi-access = free }}</ref><ref>{{cite book |edition=4th |title=The Johns Hopkins manual of gynecology and obstetrics |url=http://ovidsp.ovid.com/ovidweb.cgi?T=JS&NEWS=n&CSC=Y&PAGE=booktext&D=books&AN=01437579$&XPATH=/PG(0) |publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins |date=2011 |location=Philadelphia |isbn=978-1-4511-0913-9 | veditors = Hurt JK }}</ref>

The aim of good prenatal care is prevention, early identification, and treatment of any medical complications.<ref>{{cite book |title=Prenatal care: effectiveness and implementation |url=http://ucsfcat.library.ucsf.edu/record=b1285675~S0 |publisher=Cambridge University Press |date=1999 |location=Cambridge, UK; New York |isbn=978-0-521-66196-6 |veditors=McCormick MC, Siegel JE |access-date=10 November 2015 |archive-date=6 November 2018 |archive-url=https://web.archive.org/web/20181106190130/http://ucsfcat.library.ucsf.edu/record=b1285675~S0 }}</ref> A basic prenatal visit consists of measurement of blood pressure, [[fundal height]], weight and fetal heart rate, checking for symptoms of labor, and guidance for what to expect next.<ref name="Lyons" />

===Nutrition===
{{Main|Nutrition and pregnancy}}
[[Nutrition]] during pregnancy is important to ensure healthy growth of the fetus.<ref name="Handbook"/> Nutrition during pregnancy is different from the non-pregnant state.<ref name="Handbook" /> There are increased energy requirements and specific micronutrient requirements.<ref name="Handbook" /> Women benefit from education to encourage a balanced energy and protein intake during pregnancy.<ref>{{cite journal | vauthors = Ota E, Hori H, Mori R, Tobe-Gai R, Farrar D | title = Antenatal dietary education and supplementation to increase energy and protein intake | journal = The Cochrane Database of Systematic Reviews | volume = 2015 | issue = 6 | pages = CD000032 | date = June 2015 | pmid = 26031211 | doi = 10.1002/14651858.CD000032.pub3 }}</ref> Some women may need professional medical advice if their diet is affected by medical conditions, food allergies, or specific religious/ ethical beliefs.<ref>{{Cite web |date=2015-04-29 |title={{!}} Choose MyPlate |url=http://www.choosemyplate.gov/moms-medical-conditions |url-status=live |archive-url=https://web.archive.org/web/20151117030557/http://www.choosemyplate.gov/moms-medical-conditions |archive-date=17 November 2015 |access-date=2015-11-15 |website=Choose MyPlate }}</ref> Further studies are needed to access the effect of dietary advice to prevent [[gestational diabetes]], although low quality evidence suggests some benefit.<ref>{{cite journal | vauthors = Tieu J, Shepherd E, Middleton P, Crowther CA | title = Dietary advice interventions in pregnancy for preventing gestational diabetes mellitus | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD006674 | date = January 2017 | pmid = 28046205 | pmc = 6464792 | doi = 10.1002/14651858.CD006674.pub3 }}</ref> Adequate periconceptional (time before and right after conception) [[folic acid]] (also called folate or Vitamin B<sub>9</sub>) intake has been shown to decrease the risk of fetal neural tube defects, such as [[spina bifida]].<ref name="pmid16303691">{{cite journal | vauthors = Klusmann A, Heinrich B, Stöpler H, Gärtner J, Mayatepek E, Von Kries R | title = A decreasing rate of neural tube defects following the recommendations for periconceptional folic acid supplementation | journal = Acta Paediatrica | volume = 94 | issue = 11 | pages = 1538–1542 | date = November 2005 | pmid = 16303691 | doi = 10.1080/08035250500340396 | s2cid = 13506877 }}</ref> The neural tube develops during the first 28 days of pregnancy, a urine pregnancy test is not usually positive until 14 days post-conception, explaining the necessity to guarantee adequate folate intake before conception.<ref name="Cole" /><ref name="pmid11015508">{{cite journal | vauthors = Stevenson RE, Allen WP, Pai GS, Best R, Seaver LH, Dean J, Thompson S | title = Decline in prevalence of neural tube defects in a high-risk region of the United States | journal = Pediatrics | volume = 106 | issue = 4 | pages = 677–683 | date = October 2000 | pmid = 11015508 | doi = 10.1542/peds.106.4.677 | s2cid = 39696556 }}</ref> Folate is abundant in [[green vegetables|green leafy vegetables]], [[legume]]s, and [[citrus]].<ref>{{Cite web |title=Folic acid in diet: MedlinePlus Medical Encyclopedia |url=https://www.nlm.nih.gov/medlineplus/ency/article/002408.htm |url-status=live |archive-url=https://web.archive.org/web/20151117022119/https://www.nlm.nih.gov/medlineplus/ency/article/002408.htm |archive-date=17 November 2015 |access-date=2015-11-15 |website=www.nlm.nih.gov }}</ref> In the United States and Canada, most wheat products (flour, noodles) are fortified with folic acid.<ref name="pmid18185493">{{cite journal | title = Use of supplements containing folic acid among women of childbearing age--United States, 2007 | journal = MMWR. Morbidity and Mortality Weekly Report | volume = 57 | issue = 1 | pages = 5–8 | date = January 2008 | pmid = 18185493 | author1 = Centers for Disease Control Prevention (CDC) }}</ref>

===Weight gain===
[[File:Weight gain during pregnancy.jpg|alt=Weight gain during pregnancy|thumb| Measurement of the belly and weight are both performed by pregnant women during her pregnancy]]
The amount of healthy weight gain during a pregnancy varies.<ref name="AHRQ-weight">{{Cite journal |url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0007502/ |title=Outcomes of Maternal Weight Gain |vauthors=Viswanathan M, Siega-Riz AM, Moos MK |journal=Evidence Report/Technology Assessment |date=May 2008 |series=Evidence Reports/Technology Assessments, No. 168 |publisher=Agency for Healthcare Research and Quality |pages=1–223 |pmc=4781425 |pmid=18620471 |display-authors=etal |access-date=23 June 2013 |archive-url=https://web.archive.org/web/20130528224327/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0007502/ |archive-date=28 May 2013 |url-status=live |issue=168 }}</ref> Weight gain is related to the weight of the baby, the placenta, extra circulatory fluid, larger tissues, and fat and protein stores.<ref name="Handbook" /> Most needed weight gain occurs later in pregnancy.<ref name="IQWiG-Weight">{{Cite web |last=Institute for Quality and Efficiency in Health Care |title=Weight gain in pregnancy |url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0005004/ |url-status=live |archive-url=https://web.archive.org/web/20131214112557/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0005004/ |archive-date=14 December 2013 |access-date=23 June 2013 |website=Fact sheet |publisher=Institute for Quality and Efficiency in Health Care }}</ref>

The [[Institute of Medicine]] recommends an overall pregnancy weight gain for those of normal weight ([[body mass index]] of 18.5–24.9), of 11.3–15.9&nbsp;kg (25–35 pounds) having a singleton pregnancy.<ref>{{Cite web |title=Weight Gain During Pregnancy: Reexaminging the Guidelines, Report Brief |url=http://iom.edu/Reports/2009/Weight-Gain-During-Pregnancy-Reexamining-the-Guidelines.aspx |archive-url=https://web.archive.org/web/20100810230502/http://www.iom.edu/Reports/2009/Weight-Gain-During-Pregnancy-Reexamining-the-Guidelines.aspx |archive-date=10 August 2010 |access-date=29 July 2010 |website=Institute of Medicine }}</ref> Women who are underweight (BMI of less than 18.5), should gain between 12.7 and 18&nbsp;kg (28–40&nbsp;lb), while those who are [[overweight]] (BMI of 25–29.9) are advised to gain between 6.8 and 11.3&nbsp;kg (15–25&nbsp;lb) and those who are [[obese]] (BMI&nbsp;≥&nbsp;30) should gain between 5–9&nbsp;kg (11–20&nbsp;lb).<ref name="pmid23262962">{{cite journal | title = ACOG Committee opinion no. 548: weight gain during pregnancy | journal = Obstetrics and Gynecology | volume = 121 | issue = 1 | pages = 210–212 | date = January 2013 | pmid = 23262962 | doi = 10.1097/01.AOG.0000425668.87506.4c | author1 = American College of Obstetricians Gynecologists | doi-access = free }}</ref> These values reference the expectations for a term pregnancy.

During pregnancy, insufficient or excessive weight gain can compromise the health of the mother and fetus.<ref name=IQWiG-Weight/> The most effective intervention for weight gain in underweight women is not clear.<ref name=IQWiG-Weight/> Being or becoming overweight in pregnancy increases the risk of complications for mother and fetus, including [[Caesarean section|cesarean section]], [[gestational hypertension]], [[pre-eclampsia]], [[macrosomia]] and [[shoulder dystocia]].<ref name=AHRQ-weight/> Excessive weight gain can make losing weight after the pregnancy difficult.<ref name=AHRQ-weight/><ref name=NIHR-weight/> Some of these complications are risk factors for [[stroke]].<ref name="Bushnell">{{cite journal | vauthors = Bushnell C, McCullough LD, Awad IA, Chireau MV, Fedder WN, Furie KL, Howard VJ, Lichtman JH, Lisabeth LD, Piña IL, Reeves MJ, Rexrode KM, Saposnik G, Singh V, Towfighi A, Vaccarino V, Walters MR | title = Guidelines for the prevention of stroke in women: a statement for healthcare professionals from the American Heart Association/American Stroke Association | journal = Stroke | volume = 45 | issue = 5 | pages = 1545–1588 | date = May 2014 | pmid = 24503673 | doi = 10.1161/01.str.0000442009.06663.48 | pmc = 10152977 | s2cid = 6297484 | doi-access = free }}</ref>

Around 50% of women of childbearing age in developed countries like the United Kingdom are overweight or obese before pregnancy.<ref name="NIHR-weight">{{cite journal | vauthors = Thangaratinam S, Rogozińska E, Jolly K, Glinkowski S, Duda W, Borowiack E, Roseboom T, Tomlinson J, Walczak J, Kunz R, Mol BW, Coomarasamy A, Khan KS | title = Interventions to reduce or prevent obesity in pregnant women: a systematic review | journal = Health Technology Assessment | volume = 16 | issue = 31 | pages = iii–iv, 1–191 | date = July 2012 | pmid = 22814301 | pmc = 4781281 | doi = 10.3310/hta16310 | publisher = [[National Institute for Health and Care Research]] }}</ref> Diet modification is the most effective way to reduce weight gain and associated risks in pregnancy.<ref name=NIHR-weight/>

===Medication===
{{Main|Pharmaceutical drugs in pregnancy}}
Drugs used during pregnancy can have temporary or permanent effects on the fetus.<ref name="Briggs">{{Cite book |vauthors=Briggs GG, Freeman RK |url=http://ucsfcat.library.ucsf.edu/record=b2263003~S0 |title=Drugs in pregnancy and lactation: A Reference Guide to Fetal and Neonatal Risk |date=2015 |publisher=Wolters Kluwer/Lippincott Williams & Wilkins Health |isbn=978-1-4511-9082-3 |edition=Tenth |location=Philadelphia |page=Appendix |access-date=16 November 2015 |archive-date=25 February 2021 |archive-url=https://web.archive.org/web/20210225185426/http://ucsfcat.library.ucsf.edu/record=b2263003~S0 }}</ref> Anything (including drugs) that can cause permanent deformities in the fetus are labeled as [[teratology|teratogens]].<ref>{{Cite book |last1=Genetic Alliance |last2=The New England Public Health Genetics Education Collaborative |title=Understanding Genetics: A New England Guide for Patients and Health Professionals |date=2010-02-17 |publisher=Genetic Alliance |chapter=Appendix A: Teratogens/Prenatal Substance Abuse |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK132176/}}</ref> In the U.S., drugs were classified into categories A, B, C, D and X based on the [[Food and Drug Administration]] (FDA) rating system to provide therapeutic guidance based on potential benefits and fetal risks.<ref>{{Cite web |title=Press Announcements – FDA issues final rule on changes to pregnancy and lactation labeling information for prescription drug and biological products |url=https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm425317.htm |url-status=live |archive-url=https://web.archive.org/web/20151117040840/https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm425317.htm |archive-date=17 November 2015 |access-date=2015-11-16 |website=www.fda.gov }}</ref> Drugs, including some [[multivitamins]], that have demonstrated no fetal risks after controlled studies in humans are classified as Category A.<ref name="Briggs" /> On the other hand, drugs like [[thalidomide]] with proven fetal risks that outweigh all benefits are classified as Category X.<ref name="Briggs" />

===Recreational drugs===
{{See also|Neonatal withdrawal}}
The use of [[recreational drugs]] in pregnancy can cause various [[pregnancy complication]]s.<ref name="Williams" />
* [[Alcoholic drinks]] consumed during pregnancy can cause one or more [[fetal alcohol spectrum disorder]]s.<ref name="Williams" /> According to the [[Centers for Disease Control and Prevention|CDC]], there is no known safe amount of alcohol during pregnancy and no safe time to drink during pregnancy, including before a woman knows that she is pregnant.<ref>{{Cite web |title=Basics about FASDs |url=https://www.cdc.gov/ncbddd/fasd/facts.html |access-date=25 July 2018 |website=CDC}}</ref>
* [[Tobacco smoking and pregnancy|Tobacco smoking during pregnancy]] can cause a wide range of behavioral, neurological, and physical difficulties.<ref name="Hackshaw">{{cite journal | vauthors = Hackshaw A, Rodeck C, Boniface S | title = Maternal smoking in pregnancy and birth defects: a systematic review based on 173 687 malformed cases and 11.7 million controls | journal = Human Reproduction Update | volume = 17 | issue = 5 | pages = 589–604 | date = Sep–Oct 2011 | pmid = 21747128 | pmc = 3156888 | doi = 10.1093/humupd/dmr022 }}</ref> Smoking during pregnancy causes twice the risk of [[premature rupture of membranes]], [[placental abruption]] and [[placenta previa]].<ref name="CDC preventing">Centers for Disease Control and Prevention. 2007. [https://www.cdc.gov/nccdphp/publications/factsheets/prevention/pdf/smoking.pdf Preventing Smoking and Exposure to Secondhand Smoke Before, During, and After Pregnancy] {{webarchive|url=https://web.archive.org/web/20110911020755/http://www.cdc.gov/nccdphp/publications/factsheets/Prevention/pdf/smoking.pdf |date=11 September 2011 }}.</ref> Smoking is associated with 30% higher odds of preterm birth.<ref name="CDC tobacco use">{{cite web|url=https://www.cdc.gov/reproductivehealth/tobaccousepregnancy/index.htm|title=Tobacco Use and Pregnancy – Reproductive Health|website=www.cdc.gov|url-status=live|archive-url=https://web.archive.org/web/20170729151248/https://www.cdc.gov/reproductivehealth/tobaccoUsePregnancy/index.htm|archive-date=29 July 2017|date=2019-01-16}}</ref>
* [[Prenatal cocaine exposure]] is associated with [[preterm birth|premature birth]], [[birth defect]]s and [[attention deficit disorder]].<ref name="Williams" />
* [[Methamphetamine#Methamphetamine babies|Prenatal methamphetamine exposure]] can cause premature birth and [[congenital abnormalities]].<ref name=Fact>{{cite web|title=New Mother Fact Sheet: Methamphetamine Use During Pregnancy|url=http://www.ndmch.com|work=North Dakota Department of Health|access-date=7 October 2011|archive-url=https://web.archive.org/web/20110910221317/http://www.ndmch.com/|archive-date=10 September 2011}}</ref> Short-term neonatal outcomes in [[Methamphetamine#Methamphetamine babies|methamphetamine babies]] show small deficits in infant neurobehavioral function and growth restriction.<ref name="Grotta">{{cite journal | vauthors = Della Grotta S, LaGasse LL, Arria AM, Derauf C, Grant P, Smith LM, Shah R, Huestis M, Liu J, Lester BM | title = Patterns of methamphetamine use during pregnancy: results from the Infant Development, Environment, and Lifestyle (IDEAL) Study | journal = Maternal and Child Health Journal | volume = 14 | issue = 4 | pages = 519–527 | date = July 2010 | pmid = 19565330 | pmc = 2895902 | doi = 10.1007/s10995-009-0491-0 }}</ref> Long-term effects in terms of impaired brain development may also be caused by [[methamphetamine]] use.<ref name=Fact/>
* [[Cannabis in pregnancy]] has been shown to be [[teratogenic]] in large doses in animals, but has not shown any teratogenic effects in humans.<ref name="Williams" />

===Exposure to toxins{{anchor|Environmental toxicants and fetal development|Exposure_to_environmental_toxins}}===
{{Further|Environmental toxicants and fetal development}}
[[File:N95 Respirator Use During Advanced Pregnancy.webm|thumb|A video describing research on [[N95 respirator]] use during advanced pregnancy]]
Intrauterine exposure to [[environmental toxins in pregnancy]] has the potential to cause adverse effects on [[prenatal development]], and to cause [[Complications of pregnancy|pregnancy complications]].<ref name="Williams" /> Air pollution has been associated with low birth weight infants.<ref>{{cite book |title=Prenatal exposures: psychological and educational consequences for children |doi=10.1007/978-0-387-74398-1 |publisher=Springer |date=2008 |location=New York |isbn=978-0-387-74398-1 | vauthors = Martin R, Dombrowski SC |chapter=12. Air and Water Pollution}}</ref> Conditions of particular severity in pregnancy include [[mercury poisoning]] and [[lead poisoning]].<ref name="Williams" /> To minimize exposure to environmental toxins, the American College of Nurse-Midwives recommends: checking whether the home has [[lead paint]], washing all fresh [[fruit]]s and [[vegetable]]s thoroughly and buying [[Organic food|organic]] produce, and avoiding cleaning products labeled "toxic" or any product with a warning on the label.<ref>{{cite journal | vauthors = Byrne CC | title = Environmental hazards during pregnancy. | journal = Journal of Midwifery and Women's Health | date = 2006 | volume = 1 | issue = 51 | pages = 57–58 | doi = 10.1016/j.jmwh.2005.09.008 | pmid = 16402445 }}</ref>

Pregnant women can also be exposed to [[Chemical hazard|toxins in the workplace]], including airborne particles. The effects of wearing an [[N95 respirator|N95 filtering facepiece respirator]] are similar for pregnant women as for non-pregnant women, and wearing a respirator for one hour does not affect the fetal heart rate.<ref>{{Cite web|url=https://blogs.cdc.gov/niosh-science-blog/2015/06/18/respirators-pregnancy/|title=N95 Respirator Use During Pregnancy – Findings from Recent NIOSH Research {{!}} NIOSH Science Blog {{!}} Blogs {{!}} CDC |website=blogs.cdc.gov |date=18 June 2015 |access-date=2016-11-16|url-status=live|archive-url=https://web.archive.org/web/20161116163329/https://blogs.cdc.gov/niosh-science-blog/2015/06/18/respirators-pregnancy/|archive-date=16 November 2016}}</ref>

=== Death by violence ===
Pregnant women or those who have recently given birth in the U.S. are [[Murder of pregnant women|more likely to be murdered]] than to die from obstetric causes. These homicides are a combination of intimate partner violence and firearms. Health authorities have called the violence "a health emergency for pregnant women", but say that pregnancy-related homicides are preventable if healthcare providers identify those women at risk and offer assistance to them.<ref>{{Cite web |date=2022-10-21 |title=Homicide leading cause of death for pregnant women in U.S. |url=https://www.hsph.harvard.edu/news/hsph-in-the-news/homicide-leading-cause-of-death-for-pregnant-women-in-u-s/ |access-date=2022-11-08 |website=News |publisher=Harvard T.H. Chan School of Public Health}}</ref><ref>{{cite web |title=With homicide a leading cause of maternal death, doctors urged to screen pregnant women for domestic violence |url=https://www.cnn.com/2022/10/20/health/homicide-maternal-mortality-us-editorial/index.html |website=CNN Health |date=20 October 2022 |access-date=November 8, 2022}}</ref><ref>{{cite journal | vauthors = Wallace ME | title = Trends in Pregnancy-Associated Homicide, United States, 2020 | journal = American Journal of Public Health | volume = 112 | issue = 9 | pages = 1333–1336 | date = September 2022 | pmid = 35797500 | pmc = 9382166 | doi = 10.2105/AJPH.2022.306937 }}</ref>

===Sexual activity===
{{main|Sexual activity during pregnancy}}
Most women can continue to engage in sexual activity, including [[sexual intercourse]], throughout pregnancy.<ref name="Prenatal Care chapter">{{cite book |edition=24th |title=Williams Obstetrics |chapter-url=http://ucsfcat.library.ucsf.edu/record=b2124757~S0 |publisher=McGraw-Hill Education |date=2014 |location=New York |veditors=Cunningham FG, Leveno KJ, Bloom SL, Spong CY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS |chapter=Chapter 9: Prenatal Care |isbn=978-0-07-179893-8 |access-date=9 November 2015 |archive-date=31 December 2018 |archive-url=https://web.archive.org/web/20181231154352/http://ucsfcat.library.ucsf.edu/record=b2124757~S0 }}</ref> Research suggests that during pregnancy both sexual desire and frequency of sexual relations decrease during the first and third trimester, with a rise during the second trimester.<ref name="Bermudez">{{Cite journal |vauthors=Bermudez MP, Sanchez AI, Buela-Casal G |year=2001 |title=Influence of the Gestation Period on Sexual Desire |url=http://www.psychologyinspain.com/content/full/2001/2.htm |url-status=live |journal=Psychology in Spain |volume=5 |issue=1 |pages=14–16 |archive-url=https://web.archive.org/web/20120209172230/http://www.psychologyinspain.com/content/full/2001/2.htm |archive-date=9 February 2012 }}</ref><ref name="Fok">{{cite journal | vauthors = Fok WY, Chan LY, Yuen PM | title = Sexual behavior and activity in Chinese pregnant women | journal = Acta Obstetricia et Gynecologica Scandinavica | volume = 84 | issue = 10 | pages = 934–938 | date = October 2005 | pmid = 16167907 | doi = 10.1111/j.0001-6349.2005.00743.x | s2cid = 23075166 | doi-access = free }}</ref> I<ref name="Reamy">{{cite journal | vauthors = Reamy K, White SE, Daniell WC, Le Vine ES | title = Sexuality and pregnancy. A prospective study | journal = The Journal of Reproductive Medicine | volume = 27 | issue = 6 | pages = 321–327 | date = June 1982 | pmid = 7120209 }}</ref><ref>{{cite journal | vauthors = Malarewicz A, Szymkiewicz J, Rogala J | title = [Sexuality of pregnant women] | language = pl | journal = Ginekologia Polska | volume = 77 | issue = 9 | pages = 733–739 | date = September 2006 | pmid = 17219804 }}</ref> Sex during pregnancy is a low-risk behavior except when the healthcare provider advises that sexual intercourse be avoided for particular medical reasons.<ref name="Prenatal Care chapter" /> For a healthy pregnant woman, there is no single ''safe'' or ''right'' way to have sex during pregnancy.<ref name="Prenatal Care chapter" />

===Exercise===
[[File:A pregnant woman coming back from farm, joyfully Gisting with a elderly woman in saminaka.jpg|thumb| A pregnant woman and her colleague returning from fishing, Gurara River bridge, [[Kachia]], Nigeria.]]
Regular [[aerobic exercise]] during pregnancy appears to improve (or maintain) physical fitness.<ref>{{cite journal | vauthors = Kramer MS, McDonald SW | title = Aerobic exercise for women during pregnancy | journal = The Cochrane Database of Systematic Reviews | volume = 3 | issue = 3 | pages = CD000180 | date = July 2006 | pmid = 16855953 | pmc = 7043271 | doi = 10.1002/14651858.CD000180.pub2 | veditors = Kramer MS }}</ref> [[Physical exercise]] during pregnancy appears to decrease the need for [[C-section]],<ref>{{cite journal | vauthors = Domenjoz I, Kayser B, Boulvain M | title = Effect of physical activity during pregnancy on mode of delivery | journal = American Journal of Obstetrics and Gynecology | volume = 211 | issue = 4 | pages = 401.e1–401.11 | date = October 2014 | pmid = 24631706 | doi = 10.1016/j.ajog.2014.03.030 }}</ref> and even vigorous exercise carries no significant risks to babies<ref name="Beetham2019">{{cite journal | vauthors = Beetham KS, Giles C, Noetel M, Clifton V, Jones JC, Naughton G | title = The effects of vigorous intensity exercise in the third trimester of pregnancy: a systematic review and meta-analysis | journal = BMC Pregnancy and Childbirth | volume = 19 | issue = 1 | pages = 281 | date = August 2019 | pmid = 31391016 | pmc = 6686535 | doi = 10.1186/s12884-019-2441-1| doi-access = free }}</ref> and provides significant health benefits to the mother.<ref name="DiMascio2016">{{cite journal | vauthors = Di Mascio D, Magro-Malosso ER, Saccone G, Marhefka GD, Berghella V | title = Exercise during pregnancy in normal-weight women and risk of preterm birth: a systematic review and meta-analysis of randomized controlled trials | journal = American Journal of Obstetrics and Gynecology | volume = 215 | issue = 5 | pages = 561–571 | date = November 2016 | pmid = 27319364 | doi = 10.1016/j.ajog.2016.06.014 | hdl-access = free | s2cid = 32419788 | hdl = 11573/1110770 }}</ref> [[Bed rest]], outside of research studies, is not recommended as there is no evidence of benefit and potential harm.<ref>{{cite journal | vauthors = McCall CA, Grimes DA, Lyerly AD | title = "Therapeutic" bed rest in pregnancy: unethical and unsupported by data | journal = Obstetrics and Gynecology | volume = 121 | issue = 6 | pages = 1305–1308 | date = June 2013 | pmid = 23812466 | doi = 10.1097/aog.0b013e318293f12f }}</ref>

The Clinical Practice Obstetrics Committee of Canada recommends that "All women without contraindications should be encouraged to participate in aerobic and strength-conditioning exercises as part of a healthy lifestyle during their pregnancy".<ref name="Davies">{{cite journal | vauthors = Davies GA, Wolfe LA, Mottola MF, MacKinnon C, Arsenault MY, Bartellas E, Cargill Y, Gleason T, Iglesias S, Klein M, Martel MJ, Roggensack A, Wilson K, Gardiner P, Graham T, Haennel R, Hughson R, MacDougall D, McDermott J, Ross R, Tiidus P, Trudeau F | title = Exercise in pregnancy and the postpartum period | journal = Journal of Obstetrics and Gynaecology Canada | volume = 25 | issue = 6 | pages = 516–529 | date = June 2003 | pmid = 12806453 | doi = 10.1016/s1701-2163(16)30313-9 }}</ref> Although an upper level of safe exercise intensity has not been established, women who were regular exercisers before pregnancy and who have uncomplicated pregnancies should be able to engage in high intensity exercise programs, without a higher risk of prematurity, lower birth weight, or gestational weight gain.<ref name="Beetham2019" /> In general, participation in a wide range of recreational activities appears to be safe, with the avoidance of those with a high risk of falling such as horseback riding or skiing or those that carry a risk of abdominal trauma, such as soccer or hockey.<ref name="pmid12547738">{{cite journal | vauthors = Artal R, O'Toole M | title = Guidelines of the American College of Obstetricians and Gynecologists for exercise during pregnancy and the postpartum period | journal = British Journal of Sports Medicine | volume = 37 | issue = 1 | pages = 6–12; discussion 12 | date = February 2003 | pmid = 12547738 | pmc = 1724598 | doi = 10.1136/bjsm.37.1.6 }}</ref>

[[American College of Obstetricians and Gynecologists|The American College of Obstetricians and Gynecologists]] reports that in the past, the main concerns of exercise in pregnancy were focused on the fetus and any potential maternal benefit was thought to be offset by potential risks to the fetus. However, they write that more recent information suggests that in the uncomplicated pregnancy, fetal injuries are highly unlikely.<ref name="pmid12547738" /> They do, however, list several circumstances when a woman should contact her healthcare provider before continuing with an exercise program: vaginal bleeding, [[dyspnea]] before exertion, dizziness, headache, chest pain, muscle weakness, preterm labor, decreased fetal movement, amniotic fluid leakage, and calf pain or swelling (to rule out [[thrombophlebitis]]).<ref name="pmid12547738" />

===Sleep===
{{main|Pregnancy and sleep}}
It has been suggested that [[shift work]] and exposure to bright light at night should be avoided at least during the last trimester of pregnancy to decrease the risk of psychological and behavioral problems in the newborn.<ref name="ReiterTan2013">{{cite journal | vauthors = Reiter RJ, Tan DX, Korkmaz A, Rosales-Corral SA | title = Melatonin and stable circadian rhythms optimize maternal, placental and fetal physiology | journal = Human Reproduction Update | volume = 20 | issue = 2 | pages = 293–307 | year = 2014 | pmid = 24132226 | doi = 10.1093/humupd/dmt054 | doi-access = free }}</ref>

=== Stress ===
The children of women who had high stress levels during pregnancy are slightly more likely to have [[Externalizing behavior|externalizing behavioral problems]] such as impulsivity.<ref name=":0" /> The behavioral effect was most pronounced during early childhood.<ref name=":0">{{cite journal | vauthors = Tung I, Hipwell AE, Grosse P, Battaglia L, Cannova E, English G, Quick AD, Llamas B, Taylor M, Foust JE | title = Prenatal stress and externalizing behaviors in childhood and adolescence: A systematic review and meta-analysis | journal = Psychological Bulletin | date = November 2023 | volume = 150 | issue = 2 | pages = 107–131 | pmid = 37971856 | doi = 10.1037/bul0000407 | pmc = 10932904 | pmc-embargo-date = February 1, 2025 | s2cid = 265272043 }}</ref>

=== Dental care ===
{{see also|Prenatal dental care}}

The increased levels of [[progesterone]] and [[estrogen]] during pregnancy make [[gingivitis]] more likely; the [[gums]] become edematous, red in colour, and tend to bleed.<ref>{{Cite web|url=http://jprsolutions.info/files/final-file-5af1b556a7b4b5.85475067.pdf|title=Oral health care during pregnancy: A strategies and considerations|access-date=2 June 2018|archive-date=22 August 2018|archive-url=https://web.archive.org/web/20180822014747/http://jprsolutions.info/files/final-file-5af1b556a7b4b5.85475067.pdf}}</ref> Also a [[pyogenic granuloma]] or "pregnancy tumor", is commonly seen on the labial surface of the papilla. Lesions can be treated by local debridement or deep incision depending on their size, and by following adequate [[oral hygiene]] measures.<ref>{{cite journal | vauthors = Jafarzadeh H, Sanatkhani M, Mohtasham N | title = Oral pyogenic granuloma: a review | journal = Journal of Oral Science | volume = 48 | issue = 4 | pages = 167–175 | date = December 2006 | pmid = 17220613 | doi = 10.2334/josnusd.48.167 | doi-access = free }}</ref> There have been suggestions that severe [[Periodontal disease|periodontitis]] may increase the risk of having [[preterm birth]] and [[low birth weight]]; however, a Cochrane review found insufficient evidence to determine if [[periodontitis]] can develop adverse birth outcomes.<ref name="pmid28605006">{{cite journal | vauthors = Iheozor-Ejiofor Z, Middleton P, Esposito M, Glenny AM | title = Treating periodontal disease for preventing adverse birth outcomes in pregnant women | journal = The Cochrane Database of Systematic Reviews | volume = 2017 | issue = 6 | pages = CD005297 | date = June 2017 | pmid = 28605006 | pmc = 6481493 | doi = 10.1002/14651858.CD005297.pub3 }}</ref>

===Flying===
In low risk pregnancies, most health care providers approve flying until about 36 weeks of gestational age.<ref>{{cite book | vauthors = Howland G |title=The Mama Natural Week-by-Week Guide to Pregnancy and Childbirth |date=2017 |publisher=Simon and Schuster |isbn=978-1-5011-4668-8 |page=173 |url=https://books.google.com/books?id=7TCzCwAAQBAJ&pg=PA173}}</ref> Most airlines allow pregnant women to fly short distances at less than 36 weeks, and long distances at less than 32 weeks.<ref name=Jarvis>{{cite book | vauthors = Jarvis S, Stone J, Eddleman K, Duenwald M |title=Pregnancy For Dummies |date=2011 |publisher=John Wiley & Sons |isbn=978-1-119-99706-1 |page=157 |url=https://books.google.com/books?id=YaVwrjpeRZsC&pg=PT57}}</ref> Many airlines require a doctor's note that approves flying, especially at over 28 weeks.<ref name=Jarvis/> During flights, the risk of [[deep vein thrombosis]] is decreased by getting up and walking occasionally, as well as by avoiding dehydration. The exposure to cosmic radiation is negligible for most travelers. For pregnant women, even the longest intercontinental fight would expose them less than 15% of both the [[National Council on Radiation Protection and Measurements|NCRPM]] and [[International Commission on Radiological Protection|ICRP]] limit.<ref>{{Cite web |title=Air Travel During Pregnancy |url=https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2018/08/air-travel-during-pregnancy |access-date=2023-12-22 |website=www.acog.org}}</ref><ref name=Jarvis/> [[Full body scanner]]s do not use ionizing radiation, and are safe in pregnancy.<ref>{{cite web|url=https://www.tsa.gov/blog/2014/07/22/tsa-travel-tips-pregnant-passengers|title=TSA Travel Tips for Pregnant Passengers|date=2014-07-22|website=[[Transportation Security Administration]]|access-date=27 February 2019|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806200053/https://www.tsa.gov/blog/2014/07/22/tsa-travel-tips-pregnant-passengers}}</ref>

=== Pregnancy classes and birth plan ===
{{Main|Birthing classes and birth plans}}
To prepare for the birth of the baby, health care providers recommend that parents attend antenatal classes during the third trimester of pregnancy. Classes include information about the process of labor and birth and the various kinds of births, including both vaginal and [[caesarean delivery]], the use of forceps, and other interventions that may be needed to safely deliver the infant. Types of pain relief, including relaxation techniques, are discussed. Partners or others who may plan to support a woman during her labor and delivery learn how to assist in the birth.{{citation needed|date=September 2023}}

It is also suggested that a birth plan be written at this time. A birth plan is a written statement that outlines the desires of the mother during labor and delivery of the baby. Discussing the birth plan with the midwife or other care provider gives parents a chance to ask questions and learn more about the process of labour.<ref>{{cite web |title=Antenatal classes |url=https://www.nhs.uk/pregnancy/labour-and-birth/preparing-for-the-birth/antenatal-classes/ |website=NHS |date=December 2020 |access-date=November 16, 2022}}</ref>

In 1991 the [[WHO]] launched the [[Baby-Friendly Hospital Initiative]], a global program that recognizes birthing centers and hospitals that offer optimal levels of care for giving birth. Facilities that have been certified as "Baby Friendly" accept visits from expecting parents to familiarize them with the facility and the staff.<ref>{{cite web |title=Promoting baby-friendly hospitals |url=https://www.who.int/activities/promoting-baby-friendly-hospitals |website=World Health Organization |access-date=November 16, 2022}}</ref>

==Complications==
{{Main|Complications of pregnancy}}
Each year, ill health as a result of pregnancy is experienced (sometimes permanently) by more than 20 million women around the world.<ref name="WHO Reproductive Health and Research Publications: Making Pregnancy Safer">{{cite web|url=http://www.searo.who.int/EN/Section13/Section36/Section129/Section396_1450.htm|title=Reproductive Health and Research Publications: Making Pregnancy Safer|year=2009|publisher=World Health Organization Regional Office for South-East Asia|access-date=7 December 2009|archive-url=https://web.archive.org/web/20091215230752/http://www.searo.who.int/EN/Section13/Section36/Section129/Section396_1450.htm|archive-date=15 December 2009}}</ref> In 2016, complications of pregnancy resulted in 230,600 deaths down from 377,000 deaths in 1990.<ref name=GBD2016/> Common causes include [[maternal bleeding|bleeding]] (72,000), [[Postpartum infections|infections]] (20,000), [[Hypertensive disease of pregnancy|hypertensive diseases of pregnancy]] (32,000), [[obstructed labor]] (10,000), and [[:Category:Pregnancy with abortive outcome|pregnancy with abortive outcome]] (20,000), which includes [[miscarriage]], [[abortion]], and [[ectopic pregnancy]].<ref name=GBD2016/>

The following are some examples of pregnancy complications:
* [[Pregnancy induced hypertension]]
* [[Anemia]]<ref>{{cite web |title=Pregnancy complicated by disease|url=https://www.merckmanuals.com/home/women-s-health-issues/pregnancy-complicated-by-disease/anemia-during-pregnancy|work=Merck Manual, Home Health Handbook|publisher=Merck Sharp & Dohme}}</ref>
* [[Postpartum depression]], a common but solvable complication following childbirth that may result from decreased hormonal levels.<ref name="Stewart">{{cite journal | vauthors = Stewart DE, Vigod S | title = Postpartum Depression | journal = The New England Journal of Medicine | volume = 375 | issue = 22 | pages = 2177–2186 | date = December 2016 | pmid = 27959754 | doi = 10.1056/nejmcp1607649 }}</ref>
* [[Postpartum psychosis]]
* [[Venous thrombosis|Thromboembolic disorders]], with an increased risk due to [[hypercoagulability in pregnancy]]. These are the leading cause of death in pregnant women in the US.<ref>{{cite web|author=Lara A Friel |title=Thromboembolic Disorders During Pregnancy |url= https://www.merckmanuals.com/home/women-s-health-issues/pregnancy-complicated-by-disease/thromboembolic-disorders-during-pregnancy|publisher=Merck Sharp & Dohme Corp}}</ref><ref name=Lev2013/>
* [[Pruritic urticarial papules and plaques of pregnancy]] (PUPPP), a skin disease that develops around the 32nd week. Signs are red plaques, papules, and itchiness around the belly button that then spreads all over the body except for the inside of hands and face.
* [[Ectopic pregnancy]], including [[abdominal pregnancy]], implantation of the embryo outside the uterus
* [[Hyperemesis gravidarum]], excessive nausea and vomiting that is more severe than normal morning sickness.
* [[Pulmonary embolism]], a blood clot that forms in the legs and migrates to the lungs.<ref name=Lev2013>{{cite book | vauthors = Leveno K | title = Williams Manual of Pregnancy Complications | publisher = McGraw-Hill Medical | location = New York | year = 2013 |chapter=52|pages=323–334| isbn = 978-0-07-176562-6 }}</ref>
* [[Acute fatty liver of pregnancy]] is a rare complication thought to be brought about by a disruption in the metabolism of fatty acids by [[mitochondrion|mitochondria]].

There is also an increased [[susceptibility and severity of infections in pregnancy|susceptibility and severity of certain infections in pregnancy]].

===Miscarriage and stillbirth===
{{Main|Miscarriage|Stillbirth}}
{{See also|Miscarriage and grief}}

Miscarriage is the most common complication of early pregnancy. It is defined as the loss of an embryo or fetus before it is able to survive independently. The most common symptom of miscarriage is vaginal bleeding with or without pain. The miscarriage may be evidenced by a clot-like material passing through and out of the vagina.<ref>{{cite web |title=What are the symptoms of pregnancy loss (before 20 weeks of pregnancy)? |url=https://www.nichd.nih.gov/health/topics/pregnancyloss/conditioninfo/symptoms |website=NIH |date=September 2017 |access-date=October 4, 2022}}</ref> About 80% of miscarriages occur in the first 12 weeks of pregnancy. The underlying cause in about half of cases involves chromosomal abnormalities.<ref>{{cite web |title=Miscarriage Causes |url=https://www.webmd.com/baby/4-common-causes-miscarriage#1 |website=WebMD |access-date=October 6, 2022}}</ref>

Stillbirth is defined as fetal death after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. Each year about 21,000 babies are stillborn in the U.S.<ref>{{cite web |title=What Is Stillborn |url=https://www.cdc.gov/ncbddd/stillbirth/facts.html |website=CDC |date=29 September 2022 |access-date=October 6, 2022}}</ref> Sadness, anxiety, and guilt may occur after a miscarriage or a stillbirth. Emotional support may help with processing the loss.<ref>{{cite web |title=Miscarriage |website=NHS|url=https://www.nhs.uk/conditions/miscarriage/|date=9 March 2022}}</ref> Fathers may experience grief over the loss as well. A large study found that there is a need to increase the accessibility of support services available for fathers.<ref>{{cite journal | vauthors = Obst KL, Due C, Oxlad M, Middleton P | title = Men's grief following pregnancy loss and neonatal loss: a systematic review and emerging theoretical model | journal = BMC Pregnancy and Childbirth | volume = 20 | issue = 1 | pages = 11 | date = January 2020 | pmid = 31918681 | pmc = 6953275 | doi = 10.1186/s12884-019-2677-9 | doi-access = free }}</ref>

==Diseases in pregnancy==
{{Further|Pre-existing disease in pregnancy}}
A pregnant woman may have a [[pre-existing disease in pregnancy|pre-existing disease]], which is not directly caused by the pregnancy, but may cause [[complications of pregnancy|complications]] to develop that include a potential risk to the pregnancy; or a disease may develop during pregnancy.
* [[Diabetes mellitus and pregnancy]] deals with the interactions of [[diabetes mellitus]] (not restricted to [[gestational diabetes]]) and pregnancy. Risks for the child include miscarriage, growth restriction, growth acceleration, [[large for gestational age]] (macrosomia), [[polyhydramnios]] (too much [[amniotic fluid]]), and birth defects.
* [[Thyroid disease in pregnancy]] can, if uncorrected, cause adverse effects on fetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect [[Developmental milestone|neurointellectual development]] in the early life of the child. Demand for thyroid hormones is increased during pregnancy, which may cause a previously unnoticed thyroid disorder to worsen.
* Untreated [[celiac disease]] can cause a [[miscarriage]], [[intrauterine growth restriction]], [[small for gestational age]], [[low birthweight]] and [[preterm birth]]. Often [[Reproductive system disease|reproductive disorders]] are the only manifestation of undiagnosed celiac disease and most cases are not recognized. Complications or failures of pregnancy cannot be explained simply by [[malabsorption]], but by the [[Autoimmmune response|autoimmune response]] elicited by the exposure to [[gluten]], which causes damage to the [[placenta]]. The [[gluten-free diet]] avoids or reduces the risk of developing reproductive disorders in pregnant women with celiac disease.<ref name="TersigniCastellani2014">{{cite journal | vauthors = Tersigni C, Castellani R, de Waure C, Fattorossi A, De Spirito M, Gasbarrini A, Scambia G, Di Simone N | title = Celiac disease and reproductive disorders: meta-analysis of epidemiologic associations and potential pathogenic mechanisms | journal = Human Reproduction Update | volume = 20 | issue = 4 | pages = 582–593 | year = 2014 | pmid = 24619876 | doi = 10.1093/humupd/dmu007 | doi-access = free | hdl = 10807/56796 | hdl-access = free }}</ref><ref name="SacconeBerghella2015">{{cite journal | vauthors = Saccone G, Berghella V, Sarno L, Maruotti GM, Cetin I, Greco L, Khashan AS, McCarthy F, Martinelli D, Fortunato F, Martinelli P | title = Celiac disease and obstetric complications: a systematic review and metaanalysis | journal = American Journal of Obstetrics and Gynecology | volume = 214 | issue = 2 | pages = 225–234 | date = February 2016 | pmid = 26432464 | doi = 10.1016/j.ajog.2015.09.080 | hdl = 11369/330101 | hdl-access = free }}</ref> Also, pregnancy can be a trigger for the development of celiac disease in [[Genetic susceptibility|genetically susceptible]] women who are consuming gluten.<ref name=Glutengovca>{{cite web|title=The Gluten Connection|url=https://www.canada.ca/en/health-canada/services/food-nutrition/reports-publications/food-safety/celiac-disease-gluten-connection-1.html|publisher=Health Canada|access-date=1 October 2013|url-status=live|archive-url=https://web.archive.org/web/20170705183625/https://www.canada.ca/en/health-canada/services/food-nutrition/reports-publications/food-safety/celiac-disease-gluten-connection-1.html|archive-date=5 July 2017|date=May 2009}}</ref>
* [[Lupus and pregnancy|Lupus in pregnancy]] confers an increased rate of fetal death ''in utero,'' miscarriage, and of [[neonatal lupus]].
* [[Hypercoagulability in pregnancy]] is the propensity of pregnant women to develop [[thrombosis]] (blood clots). Pregnancy itself is a factor of [[hypercoagulability]] (pregnancy-induced hypercoagulability), as a physiologically adaptive mechanism to prevent [[postpartum hemorrhage|postpartum bleeding]].<ref name=gresele/> However, in combination with an underlying hypercoagulable state, the risk of thrombosis or embolism may become substantial.<ref name=gresele>Page 264 in: {{cite book |author=Gresele, Paolo |title=Platelets in hematologic and cardiovascular disorders: a clinical handbook |publisher=Cambridge University Press |location=Cambridge, UK |year=2008 |isbn=978-0-521-88115-9 }}</ref>

==Abortion==
{{main|Abortion}}
An abortion is the termination of an embryo or fetus via medical method. It is usually done within the first trimester, sometimes in the second, and rarely in the third. Reasons for [[unintended pregnancy|pregnancies being undesired]] are broad,<ref name="Zdanowicz 2019">{{cite web | vauthors = Zdanowicz C | title=Women have abortions for many reasons aside from rape and incest. Here are some of them | website=CNN | date=2019-05-21 | url=https://www.cnn.com/2019/05/21/health/women-reasons-abortion-trnd/index.html | access-date=2022-07-02}}</ref> [[rape]] being the most legally accepted.<ref name="Center for Reproductive Rights 2022">{{cite web | title=Law and Policy Guide: Rape and Incest Exceptions | website=[[Center for Reproductive Rights]] | date=2022-01-18 | url=https://reproductiverights.org/maps/worlds-abortion-laws/law-and-policy-guide-rape-and-incest-exceptions/ | access-date=2022-07-02}}</ref>

==Birth control and education==
{{Main|Birth control}}
[[Family planning]], as well as the availability and use of [[contraception]], along with increased [[comprehensive sex education]], has enabled many to prevent pregnancies when they are not desired. Schemes and funding to support education and the means to prevent pregnancies when they are not intended have been instrumental and are part of the third of the [[Sustainable Development Goals]] (SDGs) advanced by the [[United Nations]].<ref name="Population Division">{{cite web | title=SDG Indicator 3.7.1 on Contraceptive Use | website=Population Division | url=https://www.un.org/development/desa/pd/data/sdg-indicator-371-contraceptive-use | access-date=2022-07-03}}</ref>

==Technologies and science==
{{Further|Obstetrics}}

===Assisted reproductive technology===
{{main|Assisted reproductive technology}}
Modern reproductive medicine offers many forms of assisted reproductive technology for couples who stay childless against their will, such as [[fertility medication]], [[artificial insemination]], [[in vitro fertilization|''in vitro'' fertilization]] and [[surrogacy]].

===Medical imaging===
[[File:Volume rendered CT scan of a pregnancy of 37 weeks of gestational age (smaller).gif|thumb|[[CT scan]]ning ([[volume rendering|volume rendered]] in this case) confers a [[Absorbed dose|radiation dose]] to the developing fetus.]] [[File:Pregnancy_Check_Up.jpg|thumb|A pregnant woman undergoing an [[ultrasound]]. Ultrasound is used to check on the growth and development of the fetus.]]
{{Main|Medical imaging in pregnancy}}
[[Medical imaging]] may be [[Indication (medicine)|indicated]] in pregnancy because of [[complications of pregnancy|pregnancy complications]], disease, or routine [[prenatal care]]. [[Medical ultrasonography]] including [[obstetric ultrasonography]], and [[Magnetic resonance imaging in pregnancy|magnetic resonance imaging (MRI)]] without [[MRI contrast agent|contrast agents]] are not associated with any risk for the mother or the fetus, and are the imaging techniques of choice for pregnant women.<ref name=acog>{{cite web|url=https://www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Guidelines-for-Diagnostic-Imaging-During-Pregnancy-and-Lactation|title=Guidelines for Diagnostic Imaging During Pregnancy and Lactation|website=[[American Congress of Obstetricians and Gynecologists]]|url-status=live|archive-url=https://web.archive.org/web/20170730145349/https://www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Guidelines-for-Diagnostic-Imaging-During-Pregnancy-and-Lactation|archive-date=30 July 2017}} February 2016</ref> [[Projectional radiography]], [[CT scan]] and [[Nuclear medicine#Diagnostic|nuclear medicine imaging]] result in some degree of [[ionizing radiation]] exposure, but in most cases the [[absorbed dose]]s are not associated with harm to the baby.<ref name=acog/> At higher dosages or frequency, effects can include [[miscarriage]], [[birth defect]]s and [[intellectual disability]].<ref name=acog/>

==Epidemiology==
{{See also|Pregnancy rate|Advanced maternal age}}

About 213 million pregnancies occurred in 2012 of which 190 million were in the [[developing world]] and 23 million were in the developed world.<ref name=Sed2014/> This is about 133 pregnancies per 1,000 women aged 15 to 44.<ref name="Sed2014" /> About 10% to 15% of recognized pregnancies end in miscarriage.<ref name=John2012/> Globally, 44% of pregnancies are [[Unintended pregnancy|unplanned]]. Over half (56%) of unplanned pregnancies are aborted. In countries where [[Abortion law|abortion is prohibited]], or only carried out in circumstances where the mother's life is at risk, 48% of unplanned pregnancies are [[Illegal abortion|aborted illegally]]. Compared to the rate in countries where abortion is legal, at 69%.<ref name="Bea2018"/>

Of pregnancies in 2012, 120 million occurred in Asia, 54 million in Africa, 19 million in Europe, 18 million in Latin America and the Caribbean, 7 million in North America, and 1 million in [[Oceania]].<ref name=Sed2014/> Pregnancy rates are 140 per 1000 women of childbearing age in the developing world and 94 per 1000 in the developed world.<ref name=Sed2014/>

The rate of pregnancy, as well as the ages at which it occurs, differ by country and region. It is influenced by a number of factors, such as cultural, social and religious norms; access to contraception; and rates of education. The [[total fertility rate]] (TFR) in 2013 was estimated to be highest in [[Niger]] (7.03 children/woman) and lowest in [[Singapore]] (0.79 children/woman).<ref>{{cite web|url=https://www.cia.gov/library/publications/the-world-factbook/rankorder/2127rank.html|title=The World Factbook|work=cia.gov|archive-url=https://web.archive.org/web/20091028133713/https://www.cia.gov/library/publications/the-world-factbook/rankorder/2127rank.html|archive-date=28 October 2009}}</ref>

In Europe, the average childbearing age has been rising continuously for some time. In Western, Northern, and Southern Europe, first-time mothers are on average 26 to 29 years old, up from 23 to 25 years at the start of the 1970s. In a number of European countries (Spain), the mean age of women at first childbirth has crossed the 30-year threshold.

This process is not restricted to Europe. Asia, Japan and the United States are all seeing average age at first birth on the rise, and increasingly the process is spreading to countries in the developing world like China, Turkey and Iran. In the US, the average age of first childbirth was 25.4 in 2010.<ref>[https://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_01.pdf National Vital Statistics Reports] {{webarchive|url=https://web.archive.org/web/20170720102442/https://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_01.pdf |date=20 July 2017 }} from [[Centers for Disease Control and Prevention]] National Center for Health Statistics. Volume 61, Number 1 August 28, 2012: Births: Final Data for 2010</ref>

In the United States and United Kingdom, 40% of pregnancies are [[Unintended pregnancy|unplanned]], and between a quarter and half of those unplanned pregnancies were [[unwanted pregnancies]].<ref>{{cite news|title=40% of pregnancies 'unplanned'|url=http://news.bbc.co.uk/2/hi/health/3515400.stm|newspaper=[[BBC News]]|date=16 March 2004|url-status=live|archive-url=https://web.archive.org/web/20120730160553/http://news.bbc.co.uk/2/hi/health/3515400.stm|archive-date=30 July 2012}}</ref><ref>{{cite news| vauthors = Jayson S |title=Unplanned pregnancies in U.S. at 40 percent|url=http://www.physorg.com/news/2011-05-unplanned-pregnancies-percent.html|newspaper=[[PhysOrg.com]]|date=20 May 2011|url-status=live|archive-url=https://web.archive.org/web/20120105113426/http://www.physorg.com/news/2011-05-unplanned-pregnancies-percent.html|archive-date=5 January 2012}}</ref>

In the US, a woman's educational attainment and her marital status are correlated with childbearing: the percentage of women unmarried at the time of first birth drops with increasing educational level. In other words: among uneducated women, a large fraction (~80%) have their first child while they are unmarried. By contrast, few women with a bachelor's degree or higher (~25%) have their first child while unmarried. However, this phenomenon also has a strong generational component: in 1996, about 50% of women without a university degree had their first child being unmarried while that number increased to ~85% in 2018. Similarly, in 1996, only 4% of women with a BA degree or similar had their first child being unmarried. In 2018, that fraction increased to ~25%.<ref>{{cite journal | vauthors = Cherlin AJ | title = Rising nonmarital first childbearing among college-educated women: Evidence from three national studies | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 118 | issue = 37 | pages = e2109016118 | date = September 2021 | pmid = 34493673 | pmc = 8449381 | doi = 10.1073/pnas.2109016118 | bibcode = 2021PNAS..11809016C | doi-access = free }}</ref>


== Food and nutrition during pregnancy ==
==Legal and social aspects==
It is important for an expectant mother to eat a healthy diet. Unless she has a specific health problem (e.g., [[diabetes mellitus]] or [[edema]]) common sense nutritional advice should be followed: balancing [[carbohydrates]], [[fat]], and [[proteins]]; and eating a variety of foods, including dairy products and several fruits and vegetables, daily. A pregnant woman should consult her obstetrician for specific advice. Some specific nutritional needs for pregnancy include:


===Legal protection===
[[Folic acid]] (also called folate or Vitamin B9) is strongly needed at the start of pregnancy, and even before conception. Folic acid is needed for the closing of fetus' neural tube. It thus helps prevent [[spina bifida]], a very serious birth defect. Folates (from ''folia'', leaf) are abundant in [[spinach]] (fresh, frozen or canned), and are also found in green vegetables, salads, melon, and [[hummus]]. In the United States, most wheat products (flour, noodles) are supplemented with folic acid.
{{Further|Reproductive rights|Reproductive justice}}
Many countries have various legal regulations in place to protect pregnant women and their children. Many countries have laws against [[pregnancy discrimination]].<ref>{{Cite web |title=Maternity and paternity at work: Law and practice across the world |url=https://www.ilo.org/global/topics/equality-and-discrimination/maternity-protection/publications/maternity-paternity-at-work-2014/lang--en/index.htm |access-date=2022-09-03 |website=[[International Labour Organization]]}}</ref>


[[Maternity Protection Convention, 2000|Maternity Protection Convention]] ensures that pregnant women are exempt from activities such as night shifts or carrying heavy stocks. [[Maternity leave]] typically provides paid leave from work during roughly the last trimester of pregnancy and for some time after birth. Notable extreme cases include Norway (8 months with full pay) and the United States (no paid leave at all except in some states).
[[Calcium]] and [[iron]] are particularly needed by the rapidly growing fetus. Pregnant women should eat enough dairy products (for calcium) and red meat (for iron) if they are not vegetarian. Women are often prescribed iron pills, since many young women get slight [[anemia]]. Calcium is effective only if women also obtain enough [[Vitamin D]]. The best way to get vitamin D is to sunbathe each day for 10-15 min. Salmon and fatty fishes are also a good sources of vitamin D.


In the United States, some actions that result in miscarriage or stillbirth, such as beating a pregnant woman, are considered crimes. One law that does so is the federal [[Unborn Victims of Violence Act]]. In 2014, the American state of [[Tennessee]] passed a law which allows prosecutors to charge a woman with criminal assault if she uses illegal drugs during her pregnancy and her fetus or newborn is harmed as a result.<ref>{{cite web |url=http://www.salon.com/2014/04/30/tennessee_just_became_the_first_state_that_will_jail_women_for_their_pregnancy_outcomes/ |title=Tennessee just became the first state that will jail women for their pregnancy outcomes |author=Katie Mcdonough |date=30 April 2014 |work=Salon |access-date=5 May 2014 |url-status=live |archive-url=https://web.archive.org/web/20140505061404/http://www.salon.com/2014/04/30/tennessee_just_became_the_first_state_that_will_jail_women_for_their_pregnancy_outcomes/ |archive-date=5 May 2014 }}</ref>
[[Fluoride]] helps to build strong teeth by changing the nature of calcium crystals: if water or salt does not contain fluoride, it is wise to take fluoride mini-pills at the end of pregnancy and during breast-feeding (but high doses are toxic). In many American cities, drinking water is supplemented with fluoride. Some pregnant women suffer edema, and are told not to eat (too much) salt.


However, protections are not universal. In [[Singapore]], the ''Employment of Foreign Manpower Act'' forbids current and former [[work permit]] holders from becoming pregnant or giving birth in Singapore without prior permission.<ref name="yale">{{Cite web|url=https://yaledailynews.com/blog/2021/06/16/when-pregnancy-is-a-crime/|title = NONFICTION: When Pregnancy is a Crime|date = 17 June 2021}}</ref><ref>{{Cite web|url=https://sso.agc.gov.sg/SL/EFMA1990-S569-2012?DocDate=20210902#Sc4-|title=Employment of Foreign Manpower (Work Passes) Regulations 2012 - Singapore Statutes Online}}</ref> Violation of the Act is punishable by a fine of up to [[Singapore dollar|S$]]10,000 (US${{To USD|10000|Singapore|year=2019|r=-2}}) and [[deportation]],<ref name="yale" /><ref>{{Cite web|url=https://sso.agc.gov.sg/Act/EFMA1990?ProvIds=pr25A-#pr25A-|title=Employment of Foreign Manpower Act - Singapore Statutes Online}}</ref> and until 2010, their employers would lose their $5,000 security bond.<ref>{{cite web |url=https://twc2.org.sg/2011/07/01/employers-will-not-lose-security-bond-if-fdw-gets-pregnant-mom/ |title=Employers will not lose security bond if FDW gets pregnant – MOM |website=twc2.org.sg |date=1 July 2011 |access-date=15 December 2021 }}</ref>
[[Fat]] from salmon, trout, tuna, herring, sardine, and mackerel contain long-chain omega 3 (n-3) fatty acids that are needed to build neurone membranes. Thus fatty fish intake during pregnancy may provide nutrition for proper brain and retina development of the fetus. However, large fish such as tuna and swordfish may contain too much toxic mercury, and one should balance risks with benefits: fish two or three times a week seems to bring enough good fat, but not too much mercury.


===Teenage pregnancy===
Dangerous bacteria or parasites may contaminate foods, particularly [[listeria]] and toxoplasma, [[toxoplasmosis]] agent. To avoid those two hazards, hygiene rules should be strictly adhered to: carefully wash fruits and raw vegetables; over-cook remainders, meat and processed meat; avoid raw-milk cheeses (listeria); try to avoid contact with cat feces (toxoplasma); clean the fridge often with diluted chlorine (then rinse).
{{Main|Teenage pregnancy}}


[[Teenage pregnancy]] is also known as [[adolescent]] pregnancy.<ref name="WHO3"/> The [[World Health Organization|WHO]] defines adolescence as the period between the ages of 10 and 19 years.<ref name="WHO1">{{cite web |title=Adolescent health |url=https://www.who.int/health-topics/adolescent-health#tab=tab_1 |website=www.who.int}}</ref> Adolescents face higher health risks than women who give birth at age 20 to 24 and their infants are at a higher risk for preterm birth, low birth weight, and other severe neonatal conditions. Their children continue to face greater challenges, both behavioral and physical, throughout their lives. Teenage pregnancies are also related to social issues, including social stigma, lower educational levels, and poverty.<ref>{{cite web |title=The Adverse Effects of Teen Pregnancy |url=https://youth.gov/youth-topics/pregnancy-prevention/adverse-effects-teen-pregnancy |website=youth.gov |access-date=October 26, 2022}}</ref><ref name="WHO3">{{cite web |title=Adolescent pregnancy |url=https://www.who.int/news-room/fact-sheets/detail/adolescent-pregnancy |website=World Health Organization |access-date=October 26, 2022}}</ref> Studies show that female adolescents are often in abusive relationships at the time of their conceiving.<ref>{{cite journal |vauthors=Bekaert S, SmithBattle L |title=Teen Mothers' Experience of Intimate Partner Violence: A Metasynthesis |journal=ANS. Advances in Nursing Science |volume=39 |issue=3 |pages=272–290 |year=2016 |pmid=27490882 |doi=10.1097/ANS.0000000000000129 |s2cid=10471475 |url=https://openaccess.city.ac.uk/id/eprint/14531/1/2ANS%20IPV%20Bekaert%20and%20SmithBattle.docx}}</ref>
==Medical aspects of pregnancy==


[[Nurse-Family Partnership]] (NFP) is a non-profit organization operating in the United States and the UK designed to serve the needs of low income young mothers who may have special needs in their first pregnancy. Each mother served is partnered with a registered nurse early in her pregnancy and receives ongoing nurse home visits that continue through her child's second birthday. NFP intervention has been associated with improvements in maternal health, child health, and economic security.<ref>{{cite web |title=Nurse-Family Partnership |url=https://evidencebasedprograms.org/programs/nurse-family-partnership/ |website=Social Programs that Work |access-date=December 4, 2022}}</ref><ref>{{cite news |title=How Home Visits by Nurses Help Mothers and Children, Especially Boys |work=The New York Times |date=25 July 2017 |url=https://www.nytimes.com/2017/07/25/upshot/how-home-visits-by-nurses-help-mothers-and-children-especially-boys.html |access-date=December 6, 2022| vauthors = Miller CC }}</ref>
{{Main|Obstetrics}}
Diagnostic criteria are: In a woman who has regular menstrual cycles and is sexually active, a period delayed by a few days or weeks is suggestive of pregnancy; elevated B-hcG to around 100,000 mIU/mL by 10 weeks of gestation.


=== Racial disparities ===
[[Prenatal]] medical care is of recognized value throughout the developed world. Various Vitamins or supplements are recognized as beneficial during pregnancy. Prenatal multivitamins as well as folic acid as well as the choline available from lecithin have either government approval or published studies supporting their use. [[Folic acid]] reduces birth defects. Prenatal Choline derivable from [[lecithin]] improves the performance of rats on mental tests throughout the rats entire life. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=10531535] [[Omega 3 fatty acids]] support the mental and visual development of infants they are also beneficial postpartum. [http://www.nutraingredients-usa.com/news/ng.asp?n=70645&m=1NIU918&c=dhtelyatuhgpyxm]


There are significant racial imbalances in pregnancy and neonatal care systems.<ref name="Pereira">{{cite journal |vauthors=Pereira GM, Pimentel VM, Surita FG, Silva AD, Brito LG |title=Perceived racism or racial discrimination and the risk of adverse obstetric outcomes: a systematic review |journal=Sao Paulo Med J |volume=140 |issue=5 |pages=705–718 |date=2022 |pmid=36043663 |pmc=9514866 |doi=10.1590/1516-3180.2021.0505.R1.07042022 |url=}}</ref> Midwifery guidance, treatment, and care have been related to better birth outcomes. Diminishing racial inequities in health is an increasingly large public health challenge in the United States. Despite the fact that average rates have decreased, data on neonatal mortality demonstrates that racial disparities have persisted and grown. The death rate for African American babies is nearly double that of white neonates. According to studies, [[birth defects|congenital defects]], [[Sudden infant death syndrome|SIDS]], [[preterm birth]], and [[low birth weight]] are all more common among African American babies.<ref name="Guerra-Reyes">{{cite journal | vauthors = Guerra-Reyes L, Hamilton LJ | title = Racial disparities in birth care: Exploring the perceived role of African-American women providing midwifery care and birth support in the United States | journal = Women and Birth | volume = 30 | issue = 1 | pages = e9–e16 | date = February 2017 | pmid = 27364419 | doi = 10.1016/j.wombi.2016.06.004 }}</ref>
==Birth==
{{main|Childbirth}}
[[Childbirth]] is the process by which an infant is born. It is considered by many to be the beginning of a person's life, and age is defined relative to this event in most cultures.


Midwifery care has been linked to better birth and postpartum outcomes for both mother and child. It caters to the needs of the woman and provides competent, sympathetic care, and is essential for maternal health improvement. The presence of a [[doula]], or birth assistant, during labor and delivery, has also been associated with improved levels of satisfaction with medical birth care. Providers recognized their profession from a historical standpoint, a link to African origins, the diaspora, and prevailing African American struggles. Providers participated in both direct clinical experience and activist involvement. Advocacy efforts aimed to enhance the number of minority birth attendants and to promote the benefits of woman-centered birth care to neglected areas.<ref name="Guerra-Reyes" />
A woman is considered to be in labour when she begins experiencing regular uterine contractions, accompanied by changes of her cervix — primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labours, while others find that concentrating on the birth helps to quicken labour and lessen the sensations. Most women are capable of having a normal birth but sometimes complications arise and a woman may need to undergo a [[caesarean section]].


=== Transgender people ===
During the time immediately after birth, both baby and mother are hormonally cued to bond, the mother through the release of [[oxytocin]],a hormone also released during [[breastfeeding]].
{{Main|Transgender pregnancy}}
Transgender people have experienced significant advances in societal acceptance in recent years leaving many health professionals unprepared to provide quality care. A 2015 report suggests that "numbers of transgender individuals who are seeking family planning, fertility, and pregnancy services could certainly be quite large".
Regardless of prior hormone replacement therapy treatments, the progression of pregnancy and birthing procedures for [[Transgender pregnancy|transgender people who carry pregnancies]] are typically the same as those of [[cisgender]] women<ref>{{cite journal | vauthors = Obedin-Maliver J, Makadon HJ | title = Transgender men and pregnancy | journal = Obstetric Medicine | volume = 9 | issue = 1 | pages = 4–8 | date = March 2016 | pmid = 27030799 | pmc = 4790470 | doi = 10.1177/1753495X15612658 }}</ref> however, they may be subjected to discrimination, which can include a variety of negative social, emotional, and medical experiences, as pregnancy is regarded as an exclusively female activity. According to a study by the [[American College of Obstetricians and Gynecologists]], there is a lack of awareness, services, and medical assistance available to pregnant trans men.<ref>{{cite journal | vauthors = Light AD, Obedin-Maliver J, Sevelius JM, Kerns JL | title = Transgender men who experienced pregnancy after female-to-male gender transitioning | journal = Obstetrics and Gynecology | volume = 124 | issue = 6 | pages = 1120–1127 | date = December 2014 | pmid = 25415163 | doi = 10.1097/AOG.0000000000000540 | s2cid = 36023275 | url = https://escholarship.org/uc/item/3dz427qw }}</ref>


==Culture==
==Postnatal period==
<!-- This section has no references because it is mostly based on the German Wikipedia article. Most information here is common sense or should be easy to source. The section is intended to kickstart a more in-depth treatment. -->
{{main|Postnatal}}
[[File:Church of the Visitation IMG 0637.JPG|thumb|[[Visitation (Christianity)|The Visitation]]: [[Mary, mother of Jesus|Mary]], pregnant with [[Jesus]], visiting pregnant [[Elizabeth (biblical figure)|Elizabeth]], depicted as a statue at the [[Church of the Visitation]] in [[Ein Karem]], Israel.]]
For topics following on from a successful pregnancy and birth, see:
* [[Breastfeeding]]
* [[Child development]]
* [[Postpartum depression]]


In most cultures, pregnant women have a special status in society and receive particularly gentle care.<ref name=isbn_9780759110441/> At the same time, they are subject to expectations that may exert great psychological pressure, such as having to produce a son and heir. In many traditional societies, pregnancy must be preceded by marriage, on pain of ostracism of mother and [[Legitimacy (family law)|(illegitimate) child]].
==Medical disorders in pregnancy==
Most potentially serious problems can be anticipated and treated effectively. However, problems sometimes develop suddenly and unexpectedly. Regular visits to a doctor or midwife during pregnancy make anticipation of problems possible and improve the chances of having a healthy baby.


Overall, pregnancy is accompanied by numerous customs that are often subject to ethnological research, often rooted in [[traditional medicine]] or religion. The [[baby shower]] is an example of a modern custom.
Approximately 4 million births occur in the United States each year. A significant proportion of these are complicated by one or more medical disorders {{Fact|date=February 2007}}. A small percentage of pregnant women or new mothers have AIDS, cancer, heart disease, lung disease, physical disabilities, diabetes and pyschiatric disorders like depression.


Pregnancy is an important topic in [[sociology of the family]]. The prospective child may preliminarily be placed into numerous [[social role]]s. The parents' relationship and the relation between parents and their surroundings are also affected.
Two decades ago, many medical disorders were contra-indications to pregnancy. Advances in obstetrics, neonatology, obstetric anesthesiology, midwifery and medicine have increased the expectation that pregnancy will result in an excellent outcome for both mother and fetus despite most of these conditions. Certain medications deemed unharmful to the fetus may be highly neccessary to the welfare and benefit of the mother, especially if she has an unborn child.


A [[belly cast]] may be made during pregnancy as a keepsake.
A rare but possibly under-diagnosed disorder in pregnancy is [[Hyperemesis gravidarum]], a condition in which morning sickness is constant and extreme, resulting in dehydration and malnutrition, due to frequent vomiting.


===Arts===
==Terms and definitions==
{{Main|Pregnancy in art}}
===Technical===
Images of pregnant women, especially small [[figurine]]s, were made in traditional cultures in many places and periods, though it is rarely one of the most common types of image. These include ceramic figures from some [[Pre-Columbian]] cultures, and a few figures from most of the ancient Mediterranean cultures. Many of these seem to be connected with [[fertility in art|fertility]]. Identifying whether such figures are actually meant to show pregnancy is often a problem, as well as understanding their role in the culture concerned.
<!-- Image with unknown copyright status removed: [[Image:Expecting_mother.jpg|thumb|right|200px|Pregnant woman near the end of her third trimester]] -->
* ''embryo'' - conceptus between time of fertilization to 10 weeks of gestation
* ''fetus'' - from 10 weeks of gestation to time of birth
* ''Ga Pw-x-y-z'' - a = number of pregnancies, w = number of term births, x = number of preterm births, y = number of miscarriages, z = number of living children; for example, G4P1-2-1-3 means the woman had a total of 4 pregnancies, of which 1 is of term, 2 are preterm, 1 miscarriage, and 3 total living children (1 term + 2 preterm).
* ''Gestational age'' - time from last menstrual period (LMP) up to present
* ''gravidity (G)'' - number of times a woman has been pregnant
* ''infant'' - time of birth to 1 year of age
* ''parity (P)'' - number of pregnancies with a birth beyond 20 weeks GA or an infant weighing more than 500 g
* ''preterm infant'' - delivered between 24-37 weeks
* ''previable infant'' - delivered prior to 24 weeks
* ''term infant'' - delivered between 37-42 weeks
* ''first trimester'' - up to 14 weeks of gestation
* ''second trimester'' - 14 to 28 weeks of gestation
* ''third trimester'' - 28th week to delivery
* ''viability'' - minimum age for fetus survival, ca. third trimester
* ''zygote'' - from fertilization until second cell division
* ''full term'' refers to the end of 36 weeks (nine months) from the first day of the mother's last menstrual period — the end of gestation. If a woman gives birth earlier than this, it is classed as a ''premature birth''.


Among the oldest surviving examples of the depiction of pregnancy are prehistoric figurines found across much of [[Eurasia]] and collectively known as [[Venus figurines]]. Some of these appear to be pregnant.
===Euphemisms and colloquialisms===


Due to the important role of the [[Mother of God]] in [[Christianity]], the Western visual arts have a long tradition of depictions of pregnancy, especially in the biblical scene of the [[Visitation (Christianity)|Visitation]], and devotional images called a ''[[Madonna del Parto]]''.<ref>{{cite book| vauthors = Rossi TV |title=Mary in western art|year=2005|publisher=In Association with Hudson Hills Press|location=New York|isbn=978-0-9712981-9-4|pages=106|url=https://books.google.com/books?id=qd7EZAFouDgC&q=097129819X+pregnancy&pg=PA106}}</ref>
There are a number of [[euphemisms]] and [[colloquialisms]] for pregnancy, ranging from polite to crude, and even comical ("self-humor") terms/phrases originated from pregnant women themselves {{Fact|date=May 2007}} including: "Mother to be", "with child", "expecting", "up the duff", and "bun in the oven".


The unhappy scene usually called ''Diana and Callisto'', showing the moment of discovery of [[Callisto (mythology)|Callisto]]'s forbidden pregnancy, is sometimes painted from the Renaissance onwards. Gradually, portraits of pregnant women began to appear, with a particular fashion for "pregnancy portraits" in elite portraiture of the years around 1600.
==Regional customs==
In [[Korea]], [[China]], and [[Vietnam]], age is measured starting from conception to acknowledge that the baby exists within the mother’s body before it is born. Therefore, a newborn baby is considered to be one year old.


Pregnancy, and especially pregnancy of unmarried women, is also an important motif in literature. Notable examples include [[Thomas Hardy]]'s 1891 novel ''[[Tess of the d'Urbervilles]]'' and Goethe's 1808 play ''[[Faust: The First Part of the Tragedy|Faust]]''.
The ancient [[Mayan calendar]] of 276 days possibly originated from the human gestational cycle, or to indicate the world was created as slowly as a baby develops.


==See also==
== See also ==
* [[Couvade syndrome]]
{{wiktionary}}
*[[List of pregnancy-related topics]]
* [[Cryptic pregnancy]]
* [[False pregnancy]]
* [[Simulated pregnancy]]
*[[Pregnancy-related anxiety]]


== References ==
<br clear="all" />
{{Reflist|colwidth=30em|refs=
<ref name="isbn_9780759110441">{{Cite book | vauthors = Womack M |url=https://books.google.com/books?id=DvR53MCGx1YC&q=In+most+cultures,+pregnant+women+have+a+special+status+in+society&pg=PA133 |title=The anthropology of health and healing. |publisher=AltaMira Press |year=2010 |isbn=978-0-7591-1044-1 |location=Plymouth |pages=133 }}</ref>
}}


== Further reading ==
==References==
{{refbegin}}
<div class="references-small">
* {{Cite web |title=Nutrition for the First Trimester of Pregnancy |url=https://www.ideafit.com/personal-training/nutrition-for-the-first-trimester-of-pregnancy/ |access-date=9 December 2013 |publisher=IDEA Health & Fitness Association}}
<references />
* {{cite journal | vauthors = Bothwell TH | title = Iron requirements in pregnancy and strategies to meet them | journal = The American Journal of Clinical Nutrition | volume = 72 | issue = 1 Suppl | pages = 257S–264S | date = July 2000 | pmid = 10871591 | doi = 10.1093/ajcn/72.1.257S | doi-access = free }}
* Mittendorf R, Williams MA, Berkey CS, Cotter PF. ''The length of uncomplicated human gestation.'' Obstet Gynecol 1990;75:929-32. PMID 2342739.
* {{cite journal |author=Nguyen T, Larsen T, Engholm G, Møller H |title=Evaluation of ultrasound-estimated date of delivery in 17,450 spontaneous singleton births: do we need to modify Naegele's rule? |journal=Ultrasound Obstet Gynecol |volume=14 |issue=1 |pages=23-8 |year=1999 |id=PMID 10461334}}
* {{Cite journal | vauthors = Stevens J |title=Pregnancy envy and the politics of compensatory masculinities |journal=[[Politics & Gender]] |volume=1 |issue=2 |pages=265–296 |doi=10.1017/S1743923X05050087 |date=June 2005 |citeseerx=10.1.1.485.5791 |s2cid=39231847}}
{{refend}}
* [http://www.health.am/pregnancy/disorders-during-pregnancy/ Medical Disorders During Pregnancy]. N Engl J Med 333:1737, 2002.
* [http://www.americanpregnancy.org/gettingpregnant/earlypregnancysymptoms.html/ Pregnancy Symptoms]. American Pregnancy Association, 2005.
</div>


==External links==
== External links ==
{{Commons category|Human pregnancy}}
{{commonscat|Pregnancy}}
{{Wikiquote}}
{{wiktionarypar|Pregnant}}
* {{curlie|Health/Reproductive_Health/Pregnancy_and_Birth}}
* [http://www.wprc.org/fetal.phtml Fetal Development Photos and information]
* [https://www.merckmanuals.com/home/women-s-health-issues/pregnancy-complicated-by-disease/overview-of-disease-during-pregnancy Merck Manual Home Health Handbook] – further details on the diseases, disorders, etc., which may complicate pregnancy.
* [http://www.pregnancyweektoweek.com/ Pregnancy Week to Week] Information about every week of pregnancy
* [https://www.nhs.uk/pregnancy/your-pregnancy-care/ Pregnancy care] – NHS guide to having a baby including preconception, pregnancy, labor, and birth.
* [http://www.mayoclinic.com/health/pregnancy/HQ00451 Early pregnancy: Morning sickness, fatigue and other common symptoms, from MayoClinic.com]
* [http://www.merck.com/mrkshared/mmanual/section18/chapter249/249a.jsp Normal Pregnancy, Labor, And Delivery (Merck Manual)]
* [http://video.google.com/videoplay?docid=114199965021876684 Pregnant Women's Rights]
* Wagner, Marsden. [http://nsrc.sfsu.edu/MagArticle.cfm?Article=661 Welcoming Baby, or Not: Are men, machines, and hospitals really necessary for a healthy childbirth?] American Sexuality Magazine. Accessed 3-27-07.


{{Medical condition classification and resources
| DiseasesDB = 10545
| ICD10 = [https://icd.who.int/browse10/2019/en#/XV O00-O99], {{ICD10|Z|33||z|30}}, {{ICD10|Z34}}, {{ICD10|Z35}}
| ICD9 = {{ICD9|650}}
| MedlinePlus =002398
| eMedicineSubj =article
| eMedicineTopic =259724
| MeshID =D011247
}}
{{Pregnancy}}
{{Women's health|state=collapsed}}
{{Pathology of pregnancy, childbirth and the puerperium}}
{{Pediatric conditions originating in the perinatal period}}
{{Reproductive health}}
{{Reproductive physiology}}
{{Reproductive physiology}}
{{Human development}}
[[Category:Pregnancy|*]]
{{Sex}}
[[Category:Birth control|*]]
{{Human sexuality}}
[[Category:Biological reproduction|*]]
{{Authority control}}


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[[Category:Family]]
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[[da:Graviditet]]
[[Category:Fertility]]
[[Category:Human female endocrine system]]
[[de:Schwangerschaft]]
[[Category:Maternal health]]
[[et:Rasedus]]
[[Category:Obstetrics]]
[[el:Εγκυμοσύνη]]
[[Category:Wikipedia medicine articles ready to translate]]
[[es:Embarazo]]
[[Category:Women's health]]
[[eo:Gravedeco]]
[[eu:Haurdunaldi]]
[[fr:Grossesse]]
[[gd:Leatrom]]
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[[he:הריון]]
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Latest revision as of 05:48, 8 May 2024

Pregnancy
Other namesGestation
A woman in the third trimester of pregnancy
SpecialtyObstetrics, midwifery
SymptomsMissed periods, tender breasts, nausea and vomiting, hunger, frequent urination[1]
ComplicationsMiscarriage, high blood pressure of pregnancy, gestational diabetes, iron-deficiency anemia, severe nausea and vomiting[2][3]
Duration~40 weeks from the last menstrual period (38 weeks after conception)[4][5]
CausesSexual intercourse, assisted reproductive technology[6]
Diagnostic methodPregnancy test[7]
PreventionBirth control (including emergency contraception)[8]
TreatmentPrenatal care,[9] abortion[8]
MedicationFolic acid, iron supplements[9][10]
Frequency213 million (2012)[11]
DeathsPositive decrease 230,600 (2016)[12]

Pregnancy is the time during which one or more offspring develops (gestates) inside a woman's uterus (womb).[4][13] A multiple pregnancy involves more than one offspring, such as with twins.[14]

Pregnancy usually occurs by sexual intercourse, but can also occur through assisted reproductive technology procedures.[6] A pregnancy may end in a live birth, a miscarriage, an induced abortion, or a stillbirth. Childbirth typically occurs around 40 weeks from the start of the last menstrual period (LMP), a span known as the gestational age.[4][5] This is just over nine months. Counting by fertilization age, the length is about 38 weeks.[5][13] Pregnancy is "the presence of an implanted human embryo or fetus in the uterus"; implantation occurs on average 8–9 days after fertilization.[15] An embryo is the term for the developing offspring during the first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term fetus is used until birth.[5]

Signs and symptoms of early pregnancy may include missed periods, tender breasts, morning sickness (nausea and vomiting), hunger, implantation bleeding, and frequent urination.[1] Pregnancy may be confirmed with a pregnancy test.[7] Methods of birth control—or, more accurately, contraception—are used to avoid pregnancy.

Pregnancy is divided into three trimesters of approximately three months each. The first trimester includes conception, which is when the sperm fertilizes the egg. The fertilized egg then travels down the fallopian tube and attaches to the inside of the uterus, where it begins to form the embryo and placenta. During the first trimester, the possibility of miscarriage (natural death of embryo or fetus) is at its highest. Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies can survive outside of the uterus if provided with high-quality medical care, though babies born at this time will likely experience serious health complications such as heart and respiratory problems and long-term intellectual and developmental disabilities.

Prenatal care improves pregnancy outcomes.[9] Nutrition during pregnancy is important to ensure healthy growth of the fetus.[16] Prenatal care may also include avoiding recreational drugs (including tobacco and alcohol), taking regular exercise, having blood tests, and regular physical examinations.[9] Complications of pregnancy may include disorders of high blood pressure, gestational diabetes, iron-deficiency anemia, and severe nausea and vomiting.[3] In the ideal childbirth, labor begins on its own "at term".[17] Babies born before 37 weeks are "preterm" and at higher risk of health problems such as cerebral palsy.[4] Babies born between weeks 37 and 39 are considered "early term" while those born between weeks 39 and 41 are considered "full term".[4] Babies born between weeks 41 and 42 weeks are considered "late-term" while after 42 weeks they are considered "post-term".[4] Delivery before 39 weeks by labor induction or caesarean section is not recommended unless required for other medical reasons.[18]

Terminology

Title page from an 18th-century book about pregnancy
William Hunter, Anatomia uteri humani gravidi tabulis illustrata, 1774

Associated terms for pregnancy are gravid and parous. Gravidus and gravid come from the Latin word meaning "heavy" and a pregnant female is sometimes referred to as a gravida.[19] Gravidity refers to the number of times that a female has been pregnant. Similarly, the term parity is used for the number of times that a female carries a pregnancy to a viable stage.[20] Twins and other multiple births are counted as one pregnancy and birth.

A woman who has never been pregnant is referred to as a nulligravida. A woman who is (or has been only) pregnant for the first time is referred to as a primigravida,[21] and a woman in subsequent pregnancies as a multigravida or as multiparous.[19][22] Therefore, during a second pregnancy a woman would be described as gravida 2, para 1 and upon live delivery as gravida 2, para 2. In-progress pregnancies, abortions, miscarriages and/or stillbirths account for parity values being less than the gravida number. Women who have never carried a pregnancy more than 20 weeks are referred to as nulliparous.[23]

A pregnancy is considered term at 37 weeks of gestation. It is preterm if less than 37 weeks and postterm at or beyond 42 weeks of gestation. American College of Obstetricians and Gynecologists have recommended further division with early term 37 weeks up to 39 weeks, full term 39 weeks up to 41 weeks, and late term 41 weeks up to 42 weeks.[24] The terms preterm and postterm have largely replaced earlier terms of premature and postmature. Preterm and postterm are defined above, whereas premature and postmature have historical meaning and relate more to the infant's size and state of development rather than to the stage of pregnancy.[25][26]

Demographics and statistics

About 213 million pregnancies occurred in 2012, of which, 190 million (89%) were in the developing world and 23 million (11%) were in the developed world.[11] The number of pregnancies in women aged between 15 and 44 is 133 per 1,000 women.[11] About 10% to 15% of recognized pregnancies end in miscarriage.[2] In 2016, complications of pregnancy resulted in 230,600 maternal deaths, down from 377,000 deaths in 1990.[12] Common causes include bleeding, infections, hypertensive diseases of pregnancy, obstructed labor, miscarriage, abortion, or ectopic pregnancy.[12] Globally, 44% of pregnancies are unplanned.[27] Over half (56%) of unplanned pregnancies are aborted.[27] Among unintended pregnancies in the United States, 60% of the women used birth control to some extent during the month pregnancy began.[28]

Signs and symptoms

Melasma: pigment changes to the face due to pregnancy
In the later part of pregnancy the uterus takes up much of the abdomen.

The usual signs and symptoms of pregnancy do not significantly interfere with activities of daily living or pose a health-threat to the mother or baby. However, pregnancy complications can cause other more severe symptoms, such as those associated with anemia.

Common signs and symptoms of pregnancy include:

Timeline

Comparison of dating systems for a typical pregnancy
Event Gestational age

(from the start of the last menstrual period)

Fertilization age Implantation age
Menstrual period begins Day 1 of pregnancy Not pregnant Not pregnant
Has sex and ovulates 2 weeks pregnant Not pregnant Not pregnant
Fertilization; cleavage stage begins[32] Day 15[32] Day 1[32][33] Not pregnant
Implantation of blastocyst begins Day 20 Day 6[32][33] Day 0
Implantation finished Day 26 Day 12[32][33] Day 6 (or Day 0)
Embryo stage begins; also, first missed period 4 weeks Day 15[32] Day 9
Primitive heart function can be detected 5 weeks, 5 days[32] Day 26[32] Day 20
Fetal stage begins 10 weeks, 1 day[32] 8 weeks, 1 day[32] 7 weeks, 2 days
First trimester ends 13 weeks 11 weeks 10 weeks
Second trimester ends 26 weeks 24 weeks 23 weeks
Childbirth 39–40 weeks 37–38 weeks[33]: 108  36–37 weeks

The chronology of pregnancy is, unless otherwise specified, generally given as gestational age, where the starting point is the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. This model means that the woman is counted as being "pregnant" two weeks before conception and three weeks before implantation. Sometimes, timing may also use the fertilization age, which is the age of the embryo since conception.

Start of gestational age

The American Congress of Obstetricians and Gynecologists recommends the following methods to calculate gestational age:[34]

  • Directly calculating the days since the beginning of the last menstrual period.
  • Early obstetric ultrasound, comparing the size of an embryo or fetus to that of a reference group of pregnancies of known gestational age (such as calculated from last menstrual periods), and using the mean gestational age of other embryos or fetuses of the same size. If the gestational age as calculated from an early ultrasound is contradictory to the one calculated directly from the last menstrual period, it is still the one from the early ultrasound that is used for the rest of the pregnancy.[34]
  • In case of in vitro fertilization, calculating days since oocyte retrieval or co-incubation and adding 14 days.[35]

Trimesters

Pregnancy is divided into three trimesters, each lasting for approximately three months.[4] The exact length of each trimester can vary between sources.

  • The first trimester begins with the start of gestational age as described above, that is, the beginning of week 1, or 0 weeks + 0 days of gestational age (GA). It ends at week 12 (11 weeks + 6 days of GA)[4] or end of week 14 (13 weeks + 6 days of GA).[36]
  • The second trimester is defined as starting, between the beginning of week 13 (12 weeks +0 days of GA)[4] and beginning of week 15 (14 weeks + 0 days of GA).[36] It ends at the end of week 27 (26 weeks + 6 days of GA)[36] or end of week 28 (27 weeks + 6 days of GA).[4]
  • The third trimester is defined as starting, between the beginning of week 28 (27 weeks + 0 days of GA)[36] or beginning of week 29 (28 weeks + 0 days of GA).[4] It lasts until childbirth.
Timeline of pregnancy, including (from top to bottom): Trimesters, embryo/fetus development, gestational age in weeks and months, viability and maturity stages

Estimation of due date

Distribution of gestational age at childbirth among singleton live births, given both when gestational age is estimated by first trimester ultrasound and directly by last menstrual period.[37] Roughly 80% of births occur between 37 and 41 weeks of gestational age.

Due date estimation basically follows two steps:

  • Determination of which time point is to be used as origin for gestational age, as described in the section above.
  • Adding the estimated gestational age at childbirth to the above time point. Childbirth on average occurs at a gestational age of 280 days (40 weeks), which is therefore often used as a standard estimation for individual pregnancies.[38] However, alternative durations as well as more individualized methods have also been suggested.

The American College of Obstetricians and Gynecologists divides full term into three divisions:[39]

  • Early-term: 37 weeks and 0 days through 38 weeks and 6 days
  • Full-term: 39 weeks and 0 days through 40 weeks and 6 days
  • Late-term: 41 weeks and 0 days through 41 weeks and 6 days
  • Post-term: greater than or equal to 42 weeks and 0 days

Naegele's rule is a standard way of calculating the due date for a pregnancy when assuming a gestational age of 280 days at childbirth. The rule estimates the expected date of delivery (EDD) by adding a year, subtracting three months, and adding seven days to the origin of gestational age. Alternatively there are mobile apps, which essentially always give consistent estimations compared to each other and correct for leap year, while pregnancy wheels made of paper can differ from each other by 7 days and generally do not correct for leap year.[40]

Furthermore, actual childbirth has only a certain probability of occurring within the limits of the estimated due date. A study of singleton live births came to the result that childbirth has a standard deviation of 14 days when gestational age is estimated by first trimester ultrasound, and 16 days when estimated directly by last menstrual period.[37]

Physiology

Capacity

Fertility and fecundity are the respective capacities to fertilize and establish a clinical pregnancy and have a live birth. Infertility is an impaired ability to establish a clinical pregnancy and sterility is the permanent inability to establish a clinical pregnancy.[41]

The capacity for pregnancy depends on the reproductive system, its development and its variation, as well as on the condition of a person. Women as well as intersex and transgender people who have a functioning female reproductive system are capable of pregnancy. In some cases, someone might be able to produce fertilizable eggs, but might not have a womb or none that can sufficiently gestate, in which case they might find surrogacy.[42]

Initiation

Fertilization and implantation in humans.

Through an interplay of hormones that includes follicle stimulating hormone that stimulates folliculogenesis and oogenesis creates a mature egg cell, the female gamete. Fertilization is the event where the egg cell fuses with the male gamete, spermatozoon. After the point of fertilization, the fused product of the female and male gamete is referred to as a zygote or fertilized egg. The fusion of female and male gametes usually occurs following the act of sexual intercourse. Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation.[43] Fertilization can also occur by assisted reproductive technology such as artificial insemination and in vitro fertilisation.

Fertilization (conception) is sometimes used as the initiation of pregnancy, with the derived age being termed fertilization age. Fertilization usually occurs about two weeks before the next expected menstrual period.

A third point in time is also considered by some people to be the true beginning of a pregnancy: This is time of implantation, when the future fetus attaches to the lining of the uterus. This is about a week to ten days after fertilization.[44]

Development of embryo and fetus

The initial stages of human embryogenesis

The sperm and the egg cell, which has been released from one of the female's two ovaries, unite in one of the two fallopian tubes. The fertilized egg, known as a zygote, then moves toward the uterus, a journey that can take up to a week to complete. Cell division begins approximately 24 to 36 hours after the female and male cells unite. Cell division continues at a rapid rate and the cells then develop into what is known as a blastocyst. The blastocyst arrives at the uterus and attaches to the uterine wall, a process known as implantation.

The development of the mass of cells that will become the infant is called embryogenesis during the first approximately ten weeks of gestation. During this time, cells begin to differentiate into the various body systems. The basic outlines of the organ, body, and nervous systems are established. By the end of the embryonic stage, the beginnings of features such as fingers, eyes, mouth, and ears become visible. Also during this time, there is development of structures important to the support of the embryo, including the placenta and umbilical cord. The placenta connects the developing embryo to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. The umbilical cord is the connecting cord from the embryo or fetus to the placenta.

After about ten weeks of gestational age—which is the same as eight weeks after conception—the embryo becomes known as a fetus.[45] At the beginning of the fetal stage, the risk of miscarriage decreases sharply.[46] At this stage, a fetus is about 30 mm (1.2 inches) in length, the heartbeat is seen via ultrasound, and the fetus makes involuntary motions.[47] During continued fetal development, the early body systems, and structures that were established in the embryonic stage continue to develop. Sex organs begin to appear during the third month of gestation. The fetus continues to grow in both weight and length, although the majority of the physical growth occurs in the last weeks of pregnancy.

Electrical brain activity is first detected at the end of week 5 of gestation, but as in brain-dead patients, it is primitive neural activity rather than the beginning of conscious brain activity. Synapses do not begin to form until week 17.[48] Neural connections between the sensory cortex and thalamus develop as early as 24 weeks' gestational age, but the first evidence of their function does not occur until around 30 weeks, when minimal consciousness, dreaming, and the ability to feel pain emerges.[49]

Although the fetus begins to move during the first trimester, it is not until the second trimester that movement, known as quickening, can be felt. This typically happens in the fourth month, more specifically in the 20th to 21st week, or by the 19th week if the woman has been pregnant before. It is common for some women not to feel the fetus move until much later. During the second trimester, when the body size changes, maternity clothes may be worn.

Maternal changes

The uterus expands making up a larger and larger portion of the abdomen. During the final stages of gestation the uterus may drop to a lower position.
Breast changes as seen during pregnancy. The areolae are larger and darker.

During pregnancy, a woman undergoes many normal physiological changes, including behavioral, cardiovascular, hematologic, metabolic, renal, and respiratory changes. Increases in blood sugar, breathing, and cardiac output are all required. Levels of progesterone and estrogens rise continually throughout pregnancy, suppressing the hypothalamic axis and therefore the menstrual cycle. A full-term pregnancy at an early age (less than 25 years) reduces the risk of breast, ovarian, and endometrial cancer, and the risk declines further with each additional full-term pregnancy.[50][51]

End of second trimester + 2 weeks (26 weeks of pregnancy)

The fetus is genetically different from its mother and can therefore be viewed as an unusually successful allograft.[52] The main reason for this success is increased immune tolerance during pregnancy,[53] which prevents the mother's body from mounting an immune system response against certain triggers.[52]

During the first trimester, minute ventilation increases by 40 percent.[54] The womb will grow to the size of a lemon by eight weeks. Many symptoms and discomforts of pregnancy, such as nausea and tender breasts, appear in the first trimester.[55]

During the second trimester, most women feel more energized and put on weight as the symptoms of morning sickness subside. They begin to feel regular fetal movements, which can become strong and even disruptive.[citation needed]

Braxton Hicks contractions are sporadic uterine contractions that may start around six weeks into a pregnancy; however, they are usually not felt until the second or third trimester.[56]

Final weight gain takes place during the third trimester; this is the most weight gain throughout the pregnancy. The woman's abdomen will transform in shape as the fetus turns in a downward position ready for birth. The woman's navel will sometimes become convex, "popping" out, due to the expanding abdomen. The uterus, the muscular organ that holds the developing fetus, can expand up to 20 times its normal size during pregnancy.

Head engagement, also called "lightening" or "dropping", occurs as the fetal head descends into a cephalic presentation. While it relieves pressure on the upper abdomen and gives a renewed ease in breathing, it also severely reduces bladder capacity, resulting in a need to void more frequently, and increases pressure on the pelvic floor and the rectum. It is not possible to predict when lightening will occur. In a first pregnancy it may happen a few weeks before the due date, though it may happen later or even not until labor begins, as is typical with subsequent pregnancies.[57]

It is during the third trimester that maternal activity and sleep positions may affect fetal development due to restricted blood flow. For instance, the enlarged uterus may impede blood flow by compressing the vena cava when lying flat, a condition that can be relieved by lying on the left side.[58]

Childbirth

Childbirth, referred to as labor and delivery in the medical field, is the process whereby an infant is born.[59]

A woman is considered to be in labor when she begins experiencing regular uterine contractions, accompanied by changes of her cervix—primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labors, while others find that concentrating on the birth helps to quicken labor and lessen the sensations. Most births are successful vaginal births, but sometimes complications arise and a woman may undergo a cesarean section.

During the time immediately after birth, both the mother and the baby are hormonally cued to bond, the mother through the release of oxytocin, a hormone also released during breastfeeding. Studies show that skin-to-skin contact between a mother and her newborn immediately after birth is beneficial for both the mother and baby. A review done by the World Health Organization found that skin-to-skin contact between mothers and babies after birth reduces crying, improves mother–infant interaction, and helps mothers to breastfeed successfully. They recommend that neonates be allowed to bond with the mother during their first two hours after birth, the period that they tend to be more alert than in the following hours of early life.[60]

Childbirth maturity stages

Stages of pregnancy term
stage starts ends
Preterm[61] - at 37 weeks
Early term[62] 37 weeks 39 weeks
Full term[62] 39 weeks 41 weeks
Late term[62] 41 weeks 42 weeks
Postterm[62] 42 weeks -

In the ideal childbirth, labor begins on its own when a woman is "at term".[17] Events before completion of 37 weeks are considered preterm.[61] Preterm birth is associated with a range of complications and should be avoided if possible.[63]

Sometimes if a woman's water breaks or she has contractions before 39 weeks, birth is unavoidable.[62] However, spontaneous birth after 37 weeks is considered term and is not associated with the same risks of a preterm birth.[59] Planned birth before 39 weeks by caesarean section or labor induction, although "at term", results in an increased risk of complications.[64] This is from factors including underdeveloped lungs of newborns, infection due to underdeveloped immune system, feeding problems due to underdeveloped brain, and jaundice from underdeveloped liver.[65]

Babies born between 39 and 41 weeks' gestation have better outcomes than babies born either before or after this range.[62] This special time period is called "full term".[62] Whenever possible, waiting for labor to begin on its own in this time period is best for the health of the mother and baby.[17] The decision to perform an induction must be made after weighing the risks and benefits, but is safer after 39 weeks.[17]

Events after 42 weeks are considered postterm.[62] When a pregnancy exceeds 42 weeks, the risk of complications for both the woman and the fetus increases significantly.[66][67] Therefore, in an otherwise uncomplicated pregnancy, obstetricians usually prefer to induce labor at some stage between 41 and 42 weeks.[68]

Postnatal period

The postpartum period also referred to as the puerperium, is the postnatal period that begins immediately after delivery and extends for about six weeks.[59] During this period, the mother's body begins the return to pre-pregnancy conditions that includes changes in hormone levels and uterus size.[59]

Diagnosis

The beginning of pregnancy may be detected either based on symptoms by the woman herself, or by using pregnancy tests. However, an important condition with serious health implications that is quite common is the denial of pregnancy by the pregnant woman. About 1 in 475 denials will last until around the 20th week of pregnancy. The proportion of cases of denial, persisting until delivery is about 1 in 2500.[69] Conversely, some non-pregnant women have a very strong belief that they are pregnant along with some of the physical changes. This condition is known as a false pregnancy.[70]

Physical signs

Linea nigra in a woman at 22 weeks pregnant

Most pregnant women experience a number of symptoms,[71] which can signify pregnancy. A number of early medical signs are associated with pregnancy.[72][73] These signs include:

Biomarkers

Pregnancy detection can be accomplished using one or more various pregnancy tests,[75] which detect hormones generated by the newly formed placenta, serving as biomarkers of pregnancy.[76] Blood and urine tests can detect pregnancy by 11 and 14 days, respectively, after fertilization.[77][78] Blood pregnancy tests are more sensitive than urine tests (giving fewer false negatives).[79] Home pregnancy tests are urine tests, and normally detect a pregnancy 12 to 15 days after fertilization.[80] A quantitative blood test can determine approximately the date the embryo was fertilized because hCG levels double every 36 to 72 hours before 8 weeks' gestation.[59][78] A single test of progesterone levels can also help determine how likely a fetus will survive in those with a threatened miscarriage (bleeding in early pregnancy), but only if the ultrasound result was inconclusive.[81]

Ultrasound

Obstetric ultrasonography can detect fetal abnormalities, detect multiple pregnancies, and improve gestational dating at 24 weeks.[82] The resultant estimated gestational age and due date of the fetus are slightly more accurate than methods based on last menstrual period.[83] Ultrasound is used to measure the nuchal fold in order to screen for Down syndrome.[84]

Management

An infographic showing a flow chart leading to three diagrams, each showing two human figures depicting different lengths of gestation, with a grid showing weight limits for different locations in front of the body
Flowchart showing the recommended weight limits for lifting at work during pregnancy as a function of lifting frequency, weeks of gestation, and the position of the lifted object relative to the lifter's body.[85][86]

Prenatal care

Pre-conception counseling is care that is provided to a woman or couple to discuss conception, pregnancy, current health issues and recommendations for the period before pregnancy.[87]

Prenatal medical care is the medical and nursing care recommended for women during pregnancy, time intervals and exact goals of each visit differ by country.[88] Women who are high risk have better outcomes if they are seen regularly and frequently by a medical professional than women who are low risk.[89] A woman can be labeled as high risk for different reasons including previous complications in pregnancy, complications in the current pregnancy, current medical diseases, or social issues.[90][91]

The aim of good prenatal care is prevention, early identification, and treatment of any medical complications.[92] A basic prenatal visit consists of measurement of blood pressure, fundal height, weight and fetal heart rate, checking for symptoms of labor, and guidance for what to expect next.[87]

Nutrition

Nutrition during pregnancy is important to ensure healthy growth of the fetus.[16] Nutrition during pregnancy is different from the non-pregnant state.[16] There are increased energy requirements and specific micronutrient requirements.[16] Women benefit from education to encourage a balanced energy and protein intake during pregnancy.[93] Some women may need professional medical advice if their diet is affected by medical conditions, food allergies, or specific religious/ ethical beliefs.[94] Further studies are needed to access the effect of dietary advice to prevent gestational diabetes, although low quality evidence suggests some benefit.[95] Adequate periconceptional (time before and right after conception) folic acid (also called folate or Vitamin B9) intake has been shown to decrease the risk of fetal neural tube defects, such as spina bifida.[96] The neural tube develops during the first 28 days of pregnancy, a urine pregnancy test is not usually positive until 14 days post-conception, explaining the necessity to guarantee adequate folate intake before conception.[80][97] Folate is abundant in green leafy vegetables, legumes, and citrus.[98] In the United States and Canada, most wheat products (flour, noodles) are fortified with folic acid.[99]

Weight gain

Weight gain during pregnancy
Measurement of the belly and weight are both performed by pregnant women during her pregnancy

The amount of healthy weight gain during a pregnancy varies.[100] Weight gain is related to the weight of the baby, the placenta, extra circulatory fluid, larger tissues, and fat and protein stores.[16] Most needed weight gain occurs later in pregnancy.[101]

The Institute of Medicine recommends an overall pregnancy weight gain for those of normal weight (body mass index of 18.5–24.9), of 11.3–15.9 kg (25–35 pounds) having a singleton pregnancy.[102] Women who are underweight (BMI of less than 18.5), should gain between 12.7 and 18 kg (28–40 lb), while those who are overweight (BMI of 25–29.9) are advised to gain between 6.8 and 11.3 kg (15–25 lb) and those who are obese (BMI ≥ 30) should gain between 5–9 kg (11–20 lb).[103] These values reference the expectations for a term pregnancy.

During pregnancy, insufficient or excessive weight gain can compromise the health of the mother and fetus.[101] The most effective intervention for weight gain in underweight women is not clear.[101] Being or becoming overweight in pregnancy increases the risk of complications for mother and fetus, including cesarean section, gestational hypertension, pre-eclampsia, macrosomia and shoulder dystocia.[100] Excessive weight gain can make losing weight after the pregnancy difficult.[100][104] Some of these complications are risk factors for stroke.[105]

Around 50% of women of childbearing age in developed countries like the United Kingdom are overweight or obese before pregnancy.[104] Diet modification is the most effective way to reduce weight gain and associated risks in pregnancy.[104]

Medication

Drugs used during pregnancy can have temporary or permanent effects on the fetus.[106] Anything (including drugs) that can cause permanent deformities in the fetus are labeled as teratogens.[107] In the U.S., drugs were classified into categories A, B, C, D and X based on the Food and Drug Administration (FDA) rating system to provide therapeutic guidance based on potential benefits and fetal risks.[108] Drugs, including some multivitamins, that have demonstrated no fetal risks after controlled studies in humans are classified as Category A.[106] On the other hand, drugs like thalidomide with proven fetal risks that outweigh all benefits are classified as Category X.[106]

Recreational drugs

The use of recreational drugs in pregnancy can cause various pregnancy complications.[59]

Exposure to toxins

A video describing research on N95 respirator use during advanced pregnancy

Intrauterine exposure to environmental toxins in pregnancy has the potential to cause adverse effects on prenatal development, and to cause pregnancy complications.[59] Air pollution has been associated with low birth weight infants.[115] Conditions of particular severity in pregnancy include mercury poisoning and lead poisoning.[59] To minimize exposure to environmental toxins, the American College of Nurse-Midwives recommends: checking whether the home has lead paint, washing all fresh fruits and vegetables thoroughly and buying organic produce, and avoiding cleaning products labeled "toxic" or any product with a warning on the label.[116]

Pregnant women can also be exposed to toxins in the workplace, including airborne particles. The effects of wearing an N95 filtering facepiece respirator are similar for pregnant women as for non-pregnant women, and wearing a respirator for one hour does not affect the fetal heart rate.[117]

Death by violence

Pregnant women or those who have recently given birth in the U.S. are more likely to be murdered than to die from obstetric causes. These homicides are a combination of intimate partner violence and firearms. Health authorities have called the violence "a health emergency for pregnant women", but say that pregnancy-related homicides are preventable if healthcare providers identify those women at risk and offer assistance to them.[118][119][120]

Sexual activity

Most women can continue to engage in sexual activity, including sexual intercourse, throughout pregnancy.[121] Research suggests that during pregnancy both sexual desire and frequency of sexual relations decrease during the first and third trimester, with a rise during the second trimester.[122][123] I[124][125] Sex during pregnancy is a low-risk behavior except when the healthcare provider advises that sexual intercourse be avoided for particular medical reasons.[121] For a healthy pregnant woman, there is no single safe or right way to have sex during pregnancy.[121]

Exercise

A pregnant woman and her colleague returning from fishing, Gurara River bridge, Kachia, Nigeria.

Regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness.[126] Physical exercise during pregnancy appears to decrease the need for C-section,[127] and even vigorous exercise carries no significant risks to babies[128] and provides significant health benefits to the mother.[129] Bed rest, outside of research studies, is not recommended as there is no evidence of benefit and potential harm.[130]

The Clinical Practice Obstetrics Committee of Canada recommends that "All women without contraindications should be encouraged to participate in aerobic and strength-conditioning exercises as part of a healthy lifestyle during their pregnancy".[131] Although an upper level of safe exercise intensity has not been established, women who were regular exercisers before pregnancy and who have uncomplicated pregnancies should be able to engage in high intensity exercise programs, without a higher risk of prematurity, lower birth weight, or gestational weight gain.[128] In general, participation in a wide range of recreational activities appears to be safe, with the avoidance of those with a high risk of falling such as horseback riding or skiing or those that carry a risk of abdominal trauma, such as soccer or hockey.[132]

The American College of Obstetricians and Gynecologists reports that in the past, the main concerns of exercise in pregnancy were focused on the fetus and any potential maternal benefit was thought to be offset by potential risks to the fetus. However, they write that more recent information suggests that in the uncomplicated pregnancy, fetal injuries are highly unlikely.[132] They do, however, list several circumstances when a woman should contact her healthcare provider before continuing with an exercise program: vaginal bleeding, dyspnea before exertion, dizziness, headache, chest pain, muscle weakness, preterm labor, decreased fetal movement, amniotic fluid leakage, and calf pain or swelling (to rule out thrombophlebitis).[132]

Sleep

It has been suggested that shift work and exposure to bright light at night should be avoided at least during the last trimester of pregnancy to decrease the risk of psychological and behavioral problems in the newborn.[133]

Stress

The children of women who had high stress levels during pregnancy are slightly more likely to have externalizing behavioral problems such as impulsivity.[134] The behavioral effect was most pronounced during early childhood.[134]

Dental care

The increased levels of progesterone and estrogen during pregnancy make gingivitis more likely; the gums become edematous, red in colour, and tend to bleed.[135] Also a pyogenic granuloma or "pregnancy tumor", is commonly seen on the labial surface of the papilla. Lesions can be treated by local debridement or deep incision depending on their size, and by following adequate oral hygiene measures.[136] There have been suggestions that severe periodontitis may increase the risk of having preterm birth and low birth weight; however, a Cochrane review found insufficient evidence to determine if periodontitis can develop adverse birth outcomes.[137]

Flying

In low risk pregnancies, most health care providers approve flying until about 36 weeks of gestational age.[138] Most airlines allow pregnant women to fly short distances at less than 36 weeks, and long distances at less than 32 weeks.[139] Many airlines require a doctor's note that approves flying, especially at over 28 weeks.[139] During flights, the risk of deep vein thrombosis is decreased by getting up and walking occasionally, as well as by avoiding dehydration. The exposure to cosmic radiation is negligible for most travelers. For pregnant women, even the longest intercontinental fight would expose them less than 15% of both the NCRPM and ICRP limit.[140][139] Full body scanners do not use ionizing radiation, and are safe in pregnancy.[141]

Pregnancy classes and birth plan

To prepare for the birth of the baby, health care providers recommend that parents attend antenatal classes during the third trimester of pregnancy. Classes include information about the process of labor and birth and the various kinds of births, including both vaginal and caesarean delivery, the use of forceps, and other interventions that may be needed to safely deliver the infant. Types of pain relief, including relaxation techniques, are discussed. Partners or others who may plan to support a woman during her labor and delivery learn how to assist in the birth.[citation needed]

It is also suggested that a birth plan be written at this time. A birth plan is a written statement that outlines the desires of the mother during labor and delivery of the baby. Discussing the birth plan with the midwife or other care provider gives parents a chance to ask questions and learn more about the process of labour.[142]

In 1991 the WHO launched the Baby-Friendly Hospital Initiative, a global program that recognizes birthing centers and hospitals that offer optimal levels of care for giving birth. Facilities that have been certified as "Baby Friendly" accept visits from expecting parents to familiarize them with the facility and the staff.[143]

Complications

Each year, ill health as a result of pregnancy is experienced (sometimes permanently) by more than 20 million women around the world.[144] In 2016, complications of pregnancy resulted in 230,600 deaths down from 377,000 deaths in 1990.[12] Common causes include bleeding (72,000), infections (20,000), hypertensive diseases of pregnancy (32,000), obstructed labor (10,000), and pregnancy with abortive outcome (20,000), which includes miscarriage, abortion, and ectopic pregnancy.[12]

The following are some examples of pregnancy complications:

There is also an increased susceptibility and severity of certain infections in pregnancy.

Miscarriage and stillbirth

Miscarriage is the most common complication of early pregnancy. It is defined as the loss of an embryo or fetus before it is able to survive independently. The most common symptom of miscarriage is vaginal bleeding with or without pain. The miscarriage may be evidenced by a clot-like material passing through and out of the vagina.[149] About 80% of miscarriages occur in the first 12 weeks of pregnancy. The underlying cause in about half of cases involves chromosomal abnormalities.[150]

Stillbirth is defined as fetal death after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. Each year about 21,000 babies are stillborn in the U.S.[151] Sadness, anxiety, and guilt may occur after a miscarriage or a stillbirth. Emotional support may help with processing the loss.[152] Fathers may experience grief over the loss as well. A large study found that there is a need to increase the accessibility of support services available for fathers.[153]

Diseases in pregnancy

A pregnant woman may have a pre-existing disease, which is not directly caused by the pregnancy, but may cause complications to develop that include a potential risk to the pregnancy; or a disease may develop during pregnancy.

Abortion

An abortion is the termination of an embryo or fetus via medical method. It is usually done within the first trimester, sometimes in the second, and rarely in the third. Reasons for pregnancies being undesired are broad,[158] rape being the most legally accepted.[159]

Birth control and education

Family planning, as well as the availability and use of contraception, along with increased comprehensive sex education, has enabled many to prevent pregnancies when they are not desired. Schemes and funding to support education and the means to prevent pregnancies when they are not intended have been instrumental and are part of the third of the Sustainable Development Goals (SDGs) advanced by the United Nations.[160]

Technologies and science

Assisted reproductive technology

Modern reproductive medicine offers many forms of assisted reproductive technology for couples who stay childless against their will, such as fertility medication, artificial insemination, in vitro fertilization and surrogacy.

Medical imaging

CT scanning (volume rendered in this case) confers a radiation dose to the developing fetus.
A pregnant woman undergoing an ultrasound. Ultrasound is used to check on the growth and development of the fetus.

Medical imaging may be indicated in pregnancy because of pregnancy complications, disease, or routine prenatal care. Medical ultrasonography including obstetric ultrasonography, and magnetic resonance imaging (MRI) without contrast agents are not associated with any risk for the mother or the fetus, and are the imaging techniques of choice for pregnant women.[161] Projectional radiography, CT scan and nuclear medicine imaging result in some degree of ionizing radiation exposure, but in most cases the absorbed doses are not associated with harm to the baby.[161] At higher dosages or frequency, effects can include miscarriage, birth defects and intellectual disability.[161]

Epidemiology

About 213 million pregnancies occurred in 2012 of which 190 million were in the developing world and 23 million were in the developed world.[11] This is about 133 pregnancies per 1,000 women aged 15 to 44.[11] About 10% to 15% of recognized pregnancies end in miscarriage.[2] Globally, 44% of pregnancies are unplanned. Over half (56%) of unplanned pregnancies are aborted. In countries where abortion is prohibited, or only carried out in circumstances where the mother's life is at risk, 48% of unplanned pregnancies are aborted illegally. Compared to the rate in countries where abortion is legal, at 69%.[27]

Of pregnancies in 2012, 120 million occurred in Asia, 54 million in Africa, 19 million in Europe, 18 million in Latin America and the Caribbean, 7 million in North America, and 1 million in Oceania.[11] Pregnancy rates are 140 per 1000 women of childbearing age in the developing world and 94 per 1000 in the developed world.[11]

The rate of pregnancy, as well as the ages at which it occurs, differ by country and region. It is influenced by a number of factors, such as cultural, social and religious norms; access to contraception; and rates of education. The total fertility rate (TFR) in 2013 was estimated to be highest in Niger (7.03 children/woman) and lowest in Singapore (0.79 children/woman).[162]

In Europe, the average childbearing age has been rising continuously for some time. In Western, Northern, and Southern Europe, first-time mothers are on average 26 to 29 years old, up from 23 to 25 years at the start of the 1970s. In a number of European countries (Spain), the mean age of women at first childbirth has crossed the 30-year threshold.

This process is not restricted to Europe. Asia, Japan and the United States are all seeing average age at first birth on the rise, and increasingly the process is spreading to countries in the developing world like China, Turkey and Iran. In the US, the average age of first childbirth was 25.4 in 2010.[163]

In the United States and United Kingdom, 40% of pregnancies are unplanned, and between a quarter and half of those unplanned pregnancies were unwanted pregnancies.[164][165]

In the US, a woman's educational attainment and her marital status are correlated with childbearing: the percentage of women unmarried at the time of first birth drops with increasing educational level. In other words: among uneducated women, a large fraction (~80%) have their first child while they are unmarried. By contrast, few women with a bachelor's degree or higher (~25%) have their first child while unmarried. However, this phenomenon also has a strong generational component: in 1996, about 50% of women without a university degree had their first child being unmarried while that number increased to ~85% in 2018. Similarly, in 1996, only 4% of women with a BA degree or similar had their first child being unmarried. In 2018, that fraction increased to ~25%.[166]

Legal and social aspects

Legal protection

Many countries have various legal regulations in place to protect pregnant women and their children. Many countries have laws against pregnancy discrimination.[167]

Maternity Protection Convention ensures that pregnant women are exempt from activities such as night shifts or carrying heavy stocks. Maternity leave typically provides paid leave from work during roughly the last trimester of pregnancy and for some time after birth. Notable extreme cases include Norway (8 months with full pay) and the United States (no paid leave at all except in some states).

In the United States, some actions that result in miscarriage or stillbirth, such as beating a pregnant woman, are considered crimes. One law that does so is the federal Unborn Victims of Violence Act. In 2014, the American state of Tennessee passed a law which allows prosecutors to charge a woman with criminal assault if she uses illegal drugs during her pregnancy and her fetus or newborn is harmed as a result.[168]

However, protections are not universal. In Singapore, the Employment of Foreign Manpower Act forbids current and former work permit holders from becoming pregnant or giving birth in Singapore without prior permission.[169][170] Violation of the Act is punishable by a fine of up to S$10,000 (US$7300) and deportation,[169][171] and until 2010, their employers would lose their $5,000 security bond.[172]

Teenage pregnancy

Teenage pregnancy is also known as adolescent pregnancy.[173] The WHO defines adolescence as the period between the ages of 10 and 19 years.[174] Adolescents face higher health risks than women who give birth at age 20 to 24 and their infants are at a higher risk for preterm birth, low birth weight, and other severe neonatal conditions. Their children continue to face greater challenges, both behavioral and physical, throughout their lives. Teenage pregnancies are also related to social issues, including social stigma, lower educational levels, and poverty.[175][173] Studies show that female adolescents are often in abusive relationships at the time of their conceiving.[176]

Nurse-Family Partnership (NFP) is a non-profit organization operating in the United States and the UK designed to serve the needs of low income young mothers who may have special needs in their first pregnancy. Each mother served is partnered with a registered nurse early in her pregnancy and receives ongoing nurse home visits that continue through her child's second birthday. NFP intervention has been associated with improvements in maternal health, child health, and economic security.[177][178]

Racial disparities

There are significant racial imbalances in pregnancy and neonatal care systems.[179] Midwifery guidance, treatment, and care have been related to better birth outcomes. Diminishing racial inequities in health is an increasingly large public health challenge in the United States. Despite the fact that average rates have decreased, data on neonatal mortality demonstrates that racial disparities have persisted and grown. The death rate for African American babies is nearly double that of white neonates. According to studies, congenital defects, SIDS, preterm birth, and low birth weight are all more common among African American babies.[180]

Midwifery care has been linked to better birth and postpartum outcomes for both mother and child. It caters to the needs of the woman and provides competent, sympathetic care, and is essential for maternal health improvement. The presence of a doula, or birth assistant, during labor and delivery, has also been associated with improved levels of satisfaction with medical birth care. Providers recognized their profession from a historical standpoint, a link to African origins, the diaspora, and prevailing African American struggles. Providers participated in both direct clinical experience and activist involvement. Advocacy efforts aimed to enhance the number of minority birth attendants and to promote the benefits of woman-centered birth care to neglected areas.[180]

Transgender people

Transgender people have experienced significant advances in societal acceptance in recent years leaving many health professionals unprepared to provide quality care. A 2015 report suggests that "numbers of transgender individuals who are seeking family planning, fertility, and pregnancy services could certainly be quite large". Regardless of prior hormone replacement therapy treatments, the progression of pregnancy and birthing procedures for transgender people who carry pregnancies are typically the same as those of cisgender women[181] however, they may be subjected to discrimination, which can include a variety of negative social, emotional, and medical experiences, as pregnancy is regarded as an exclusively female activity. According to a study by the American College of Obstetricians and Gynecologists, there is a lack of awareness, services, and medical assistance available to pregnant trans men.[182]

Culture

The Visitation: Mary, pregnant with Jesus, visiting pregnant Elizabeth, depicted as a statue at the Church of the Visitation in Ein Karem, Israel.

In most cultures, pregnant women have a special status in society and receive particularly gentle care.[183] At the same time, they are subject to expectations that may exert great psychological pressure, such as having to produce a son and heir. In many traditional societies, pregnancy must be preceded by marriage, on pain of ostracism of mother and (illegitimate) child.

Overall, pregnancy is accompanied by numerous customs that are often subject to ethnological research, often rooted in traditional medicine or religion. The baby shower is an example of a modern custom.

Pregnancy is an important topic in sociology of the family. The prospective child may preliminarily be placed into numerous social roles. The parents' relationship and the relation between parents and their surroundings are also affected.

A belly cast may be made during pregnancy as a keepsake.

Arts

Images of pregnant women, especially small figurines, were made in traditional cultures in many places and periods, though it is rarely one of the most common types of image. These include ceramic figures from some Pre-Columbian cultures, and a few figures from most of the ancient Mediterranean cultures. Many of these seem to be connected with fertility. Identifying whether such figures are actually meant to show pregnancy is often a problem, as well as understanding their role in the culture concerned.

Among the oldest surviving examples of the depiction of pregnancy are prehistoric figurines found across much of Eurasia and collectively known as Venus figurines. Some of these appear to be pregnant.

Due to the important role of the Mother of God in Christianity, the Western visual arts have a long tradition of depictions of pregnancy, especially in the biblical scene of the Visitation, and devotional images called a Madonna del Parto.[184]

The unhappy scene usually called Diana and Callisto, showing the moment of discovery of Callisto's forbidden pregnancy, is sometimes painted from the Renaissance onwards. Gradually, portraits of pregnant women began to appear, with a particular fashion for "pregnancy portraits" in elite portraiture of the years around 1600.

Pregnancy, and especially pregnancy of unmarried women, is also an important motif in literature. Notable examples include Thomas Hardy's 1891 novel Tess of the d'Urbervilles and Goethe's 1808 play Faust.

See also

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Further reading

External links