fertility
As fertility or fertility , and reproductive ability , the ability is called, descendants ( " fruits ") produce. The opposite is sterility .
Definitions
The terms fertility and fertility as well as the variants derived from them are used in different contexts:
- In botany, the flowers of plants in the state of seed maturity are called fruits in the narrower sense ; in a broader sense, this term is also applied to other multicellular organisms. In earlier usage, the word “fruit of the body” was therefore also the name for a human embryo or fetus . In medicine and biology, the synonym fertility (from the Latin fertilis = fertile, productive, fertilizing) is used in relation to humans.
- As Fekundabilität the likelihood a pregnant per menstrual cycle to achieve, inscribed and expressed as a percentage.
- The fecundity is the number of successful of pregnancies per female individual.
- In a figurative sense, the fertility of a person or a people stands for their own creativity , creativity and strength .
- In demography , the total fertility rate (TFR) is an arithmetical average that indicates the number of children that an (average) woman gives birth in the course of her life - usually between the ages of 15 and 45.
- In geology , one speaks of a fertile mantle if one of its chemical components has not yet been depleted by partial melting .
Disambiguation
The fertility of a plant species is a measure of the number of new plants that are produced during each reproductive cycle. It determines how much this plant species spreads in an area when the first plants of this species appear in this area or how great the ability of this plant species is to maintain or increase the population of specimens in an area despite competition from other plant species .
Fertility in relation to human reproduction is a term that is deeply rooted in human history. It has to do with survival in two ways:
- On the one hand by the agriculture and thus began more than 10,000 years ago agriculture , leading to the development of today's material culture contributed decisively. In this context, soil fertility , but also the fertility of cattle, played an important role. There are numerous approaches to increase these forms of fertility and thus increase the yield. Fertilizing the soil or breeding livestock species that are particularly easy to reproduce are only two of the most frequently used methods.
- On the other hand, through human fertility, i.e. the fertility of men and the childbearing ability of women. In this context, fertility rites and symbols of fertility can be found in all cultures as well as influences from deities in religions and beliefs .
Conservation level
Fertility and mortality are the factors influencing natural population growth . The most industrialized countries fall short since the 1970s, the "magic threshold" of 2.1 children per woman, the replacement level , even simple replacement level and replacement level of fertility named below which decreases the population in the long term. The conservation level is the average number of children per woman ( total fertility rate ) that would be required to keep the population constant under the given mortality rates.
External factors that change fertility
Temporal influences
The phase of human life in which it is fertile and fertile begins with puberty and ends for women with menopause ( climacteric ). Female fertility peaks in her early 20s and begins to decline significantly after age 35. The Menopause usually occurs between the ages of 45 and 55 a, average age 50 to 51 years. Men, on the other hand, can be reproductive well into old age. However, the quality of the sperm can decrease with age.
Environmental factors
Human fertility can be negatively affected by various influences, such as illnesses or exposure to (environmental) toxins. This includes B. the consumption of alcohol or chronic lead poisoning . Heavy smoking damages the uterus and reduces fertility, because the fertilized egg cell can only implant in the endometrium with difficulty . In one study, half of women who smoked became pregnant, compared to only a third of women who smoked heavily. “ Perfluorinated and polyfluorinated chemicals (PFC) are some of the longest-lived chemicals that chemists have come up with, and they can reduce fertility not only in animals, but apparently also in humans. The higher the concentration of perfluorooctanoic acid (PFOA) or perfluorohexanesulfonic acid (PFHxS) in a woman's blood, the longer it took to become pregnant or the more likely it was that she would need therapy for infertility . This is a result of the Canadian MIREC study (Maternal-Infant Research on Environmental Chemicals), which examined the largest number of pregnant women to date in order to determine the possible harmful effects of environmental chemicals on pregnancy and child health. "
Nutrition and health care, but also civilizational influences such as the existence of training facilities or the possibility of coordinating child-rearing and one's own needs, also determine the fertility of any group of humanity, both within the framework of the states and within the framework of other groupings (cities, Regions, social groups).
See also
literature
- Thomas Weiss: Economic determinants of fertility in western industrialized countries (= Federal Institute for Population Research . Special issue 5). Wiesbaden 1986, ISSN 0178-918X .
- Ulla Rahn-Huber: Course book menopause. 4th edition, Südwest-Verlag, Munich 2005, ISBN 3-517-06399-1 .
- Gerhard Thews , Peter Vaupel: Vegetative Physiology. 5th edition, Springer, Heidelberg 2005, ISBN 3-540-24070-5 .
- Rainer Wehrhahn; Verena Sandner Le Gall: Population geography. Wissenschaftliche Buchgesellschaft (WBG), Darmstadt 2011, ISBN 978-3-534-15628-3 , pp. 26-36.
Web links
- Article in the online manual of the Berlin Institute for Population and Development "Fertility and Birth Development "
- BiB-Demographie.de - website of the Federal Institute for Population Research
- Fertility disorders on Familienplanung.de : The information portal of the Federal Center for Health Education (BZgA)
Individual evidence
- ↑ Rostock Center for Research into Demographic Change (RZ): Glossary of Demographic Terms [1] , accessed on February 19, 2019
- ↑ Online edition of " Human Reproduction ", quoted from Direkter Schaden. In: Süddeutsche Zeitung . from January 4, 2007, p. 18.
- ↑ Martina Lenzen-Schulte: Harmful chemicals. Pans and wild boar liver under suspicion . On: FAZ-online from February 9, 2015; last accessed on October 15, 2016.