Woe

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Labor recorder : The number on the left is the heart rate of the unborn child.

A contraction is a muscle contraction of the uterine muscle during pregnancy ( gestation or pregnancy ) and under the birth in mammals . The name is derived from the expressions of pain (the "pain") of the woman giving birth, which causes the pain. Labor is the term used to describe muscle contractions that have an impact on childbirth, be it by shortening or opening the cervix or by moving the fetus towards the pelvic floor .

But contractions can also arise during pregnancy (pregnancy contractions, subsidence contractions) and they occur more frequently immediately before and during the birth (labor contractions). The individual contractions are each 20 to 60 seconds long and their frequency depends on the type of labor. Contractions of the uterus during menstruation are not referred to as labor .

The method of choice to measure and document contractions is tokometry.

description

Labor is rhythmic muscle contractions of the uterus during pregnancy and childbirth . As every muscle has to train, the smooth muscles of the uterus are also dependent on optimizing the insufficient connections and weak expansion of the conduction of excitation of these muscle cells at the beginning of pregnancy so that they ultimately meet the requirements of childbirth. While these labor pains are usually short and painless and are often barely noticed by women, labor pains are very painful.

Labor is both the driving force behind setting the fetus into the birth canal and driving the unborn child out of the womb. Individual contractions are clearly delimited from one another in terms of time; strength and frequency increase in the course of birth. They are each 20 to 60 seconds long and their frequency depends on the type of labor.

Types of labor and phases of delivery

There are different types of labor during and after pregnancy and childbirth:

A recorded cardiotocogram (CTG)
Stages of birth when squeezing the child
  • Premature labor, including pregnancy labor or sagging labor, occurs before the 20th week of pregnancy , especially when the uterus is displaced. They are usually painless and are noticeable as a slight tug in the abdomen. In very rare cases, they can become worse and lead to premature delivery . In these cases tocolytics are used to reduce and inhibit labor . It is difficult to differentiate from (painful) labor pains (see below).
  • Exercise contractions, known as Braxton Hicks contraction , can occur from about the 25th week of pregnancy. The whole stomach becomes hard. Exercise contractions that last longer than a minute or cause severe pain require control by a midwife or doctor. Towards the end of pregnancy (approx. From the 36th week) the practice contractions turn into pre-contractions .
  • Pre-contractions are irregular contractions and vary in pain. They occur in the weeks and days before the birth as an introductory part of the same and are also known as sink pains or signal boxes , as they push the unborn child into the mother's pelvis and bring it into the birth canal . During this time it can be observed that the pregnant woman's belly gradually sags .
  • Opening contractions are regularly recurring contractions at the beginning of the actual labor process that increase in strength and frequency. They start about 10 to 12 hours before birth, and much later in the case of multiple births, and are each 10 to 15 minutes apart. They are used to completely open the cervix to the required ten centimeters and usually also lead to rupture of the bladder .
  • Compression and expulsion contractions are contractions that push the child through the cervix and the vagina and should be supported by the woman giving birth by pressing hard. They are supported by the abdominal muscles . This phase can last up to 3 hours for first-time women, and sometimes only 30 to 60 minutes for multiple women. The intensity and frequency of contractions increases, sometimes up to 5 contractions can occur within 10 minutes.
  • Demand or Nachgeburtswehen are contractions after the actual birth process leading to the detachment and expulsion of the placenta lead. This usually takes place within 30 to 60 minutes after the birth of the child and takes place by vigorously contracting the uterus, which also reduces the wound surface and thus the bleeding.
  • Post- labor pains are labor that occurs in the days after the birth, i.e. the puerperium , and supports the regression of the uterus (involute uteri) and hemostasis . They usually occur always, but at multiparas well as in mothers who brought their children quiet (Still contractions) stronger and more painful. With these, it does not take long for the uterus to return to its original size. When breastfeeding, the stimulus on the nipples releases oxytocin from the posterior lobe of the pituitary gland , which has a labor-promoting effect even after birth.

physiology

The oxytocin produced in the pituitary gland triggers labor and delivery

The hormone that triggers labor is oxytocin , which is produced in the pituitary gland ( posterior pituitary gland ). The release of oxytocin and the labor itself are triggered by various factors, including the decrease in progesterone concentration and the increase in prostaglandins in the blood as well as nerve stimulation from the vagina and uterus. This usually happens around 250 to 185 days after fertilization in the 38th to 42nd week of pregnancy.

During pregnancy, the number of oxytocin receptors in the uterine wall increases and the uterine muscles are prepared for birth by the very high level of estrogen in the blood during pregnancy by lowering the membrane potential of the uterine smooth muscles . By the increased release of prostaglandins directly before the birth of the cervix and are cervix softened so that they can be opened during birth for the passage of the child. This hormonal preparation means that the uterus is prepared for this at the time of birth. The excitability and the ability to co-ordinate contraction as well as the contraction force of the muscles are increased. The final trigger for the release of oxytocin is likely to come from the child who, if the child was born correctly, presses their head on the stretch receptors in the cervix.

The oxytocin is released from the pituitary gland into the bloodstream and attaches to the receptors in the uterine muscles. It excites them intermittently, as it is broken down again very quickly by the enzyme oxytocinase after each activation. In addition, the oxytocin stimulates the further formation of prostaglandins, which also have an activating effect on the muscles. The tone of the sympathetic nervous system is also increased and supports the woman in labor work. The contractions themselves start from a pacemaker center of spontaneously activated muscle cells, which pass the excitation on to other cells and thus the entire organ at a speed of around 2 centimeters per second, which leads to coordinated contraction.

Labor activity is measured in Montevideo units (MU), which indicate labor activity as the product of the number of contractions per ten minutes and the maximum pressure (intrauterine pressure in mmHg). The pre-contractions reach about 20 ME, corresponding to one contraction per ten minutes with a pressure of 20 mmHg. With the opening phase the labor frequency increases to 3 contractions per ten minutes with 30 to 50 mmHg pressure, whereby the head is pressed into the cervix and the cervical canal increasingly opens. The stretching of the tissues and the surrounding pelvis causes pain. In the further expulsion phase and the stretching of the cervix, further nerve impulses from the stretch receptors and the release of oxytocin are further stimulated ( Ferguson reflex ), at the same time there is further activation of the pacemaker center and the reflex motor skills of the abdominal and diaphragm muscles around the To support pressing process. Pressure values ​​of 40 to 80 mmHg are reached in the compression contractions and the typical frequency of labor is 4 to 5 contractions per 10 minutes, which corresponds to about 270 ME.

Labor measurement

The contractions are controlled by touching the abdomen with the hand or by means of a pressure-sensitive device, the tokograph (contractions recorder). In parallel to the labor measurement, the child's heartbeat is checked and assessed at regular intervals before the birth, either using the Pinard wooden tube or using the ultrasound pickup of a cardiotocograph (CTG) or Dopton .

Promotion and reduction of labor

As a rule, there is no medical intervention in the birth process, as it is a natural process. In individual cases, however, medical measures are necessary to reduce or promote labor activity. This can be necessary with various labor anomalies (labor dystocia).

The inhibition of labor (tocolysis) is mainly used when labor activity starts too early in pregnancy and there is a risk of premature birth . It may also be necessary in a too early performed rupture of membranes , ie the tearing of the amniotic sac , with very strong labor education during the early birth and during surgery on the uterus during pregnancy. As a rule, contraception is inhibited by calming down and bed rest as well as medication by the administration of contraceptive drugs such as the sympathomimetic fenoterol , sedatives and magnesium sulfate .

A labor promotion may be required if a birth due to the slow transfer to be initiated on the expected date of birth out or for other reasons, or if the natural labor intensity is too weak at birth or through muscle fatigue decreases again ( uterine inertia ) so that the process of birth and the child are at risk. Various means and methods are used to initiate labor. Various stimulants such as coffee and black tea as well as nicotine can trigger contractions . Warm baths, enemas or an orgasm can also induce labor. As House and midwives means also are labor cocktails mixed from different stimulants and drinking. In terms of medication, labor is intensified by the sex hormone oxytocin , which is administered intravenously via a so-called contraction drip and is intended to stimulate the uterus, or by prostaglandins , which are placed in the form of a gel or suppository in front of the cervix and induce labor . Ergotamines , which cause the uterus to contract continuously, can also be used to stop bleeding after birth .

In the case of an overdose of labor-promoting agents and also with natural contractions, a contractions or convulsive labor can occur in rare cases , in which the uterus cramps .

Objectively, the pain in labor can be alleviated by various medications or anesthetic methods (e.g. epidural anesthesia ). However, medications and procedures can have a negative effect on the birth. On the one hand, the length of the birth, as it can reduce the effectiveness of labor itself and make it difficult for the labor force to work. On the other hand, it also affects the child, as the pain reliever substances can also get into the bloodstream and thus also into the child's bloodstream.

See also

supporting documents

  1. ↑ a b c d e f labor . In: Pschyrembel Dictionary Sexuality. Berlin 2006, p. 1586.
  2. ↑ a b c d labor . In: Pschyrembel Medical Dictionary. 257th edition. De Gruyter, Berlin 1993, ISBN 3-933203-04-X , p. 1658.
  3. ↑ a b c d e f Arne Schäffler, Nicole Menche: Human - Body - Illness. 3. Edition. Urban & Fischer, Munich 1999, pp. 416-418.
  4. ↑ a b Rainer Klinke, Stefan Silbernagl (ed.): Textbook of Physiology. 2nd Edition. Thieme, Stuttgart 1994, ISBN 3-13-796002-9 , p. 451.
  5. ↑ a b c d e f g Rainer Klinke, Stefan Silbernagl (ed.): Textbook of Physiology. 2nd Edition. Thieme, Stuttgart 1994, ISBN 3-13-796002-9 , pp. 503-505.
  6. ↑ a b labor dystocia . In: Pschyrembel Medical Dictionary. 257th edition. De Gruyter, Berlin 1993, ISBN 3-933203-04-X , pp. 1658-1659.
  7. ↑ Inhibition of labor . In: Pschyrembel Dictionary Sexuality. Berlin 2006, p. 1586.
  8. ↑ weak contractions . In: Pschyrembel Dictionary Sexuality. Berlin 2006, p. 1586.
  9. ↑ a b parturifacient . In: Pschyrembel Medical Dictionary. 257th edition. De Gruyter, Berlin 1993, ISBN 3-933203-04-X , pp. 1658-1659.
  10. ↑ labor promotion . In: Pschyrembel Dictionary Sexuality. Berlin 2006, p. 1586.
  11. ↑ Wehsturm . In: Pschyrembel Dictionary Sexuality. Berlin 2006, p. 1586.
  12. ↑ Birth with PDA (PeriDual Anesthesia) . In: Hello parents . January 11, 2016 ( hallo-eltern.de [accessed July 13, 2018]).

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