how Effect of fettal hormone on the uterus causes parturition

Answer 1

The process of parturition, or childbirth, is primarily regulated by the hormonal changes that occur in the mother's body, including the effect of fetal hormones on the uterus. These hormones play a crucial role in preparing the uterus for labor and promoting the start of contractions.

One of the key fetal hormones involved in parturition is cortisol, which is produced by the fetal adrenal glands in response to stress. As the pregnancy advances, the levels of cortisol in the fetal blood increase and reach a peak just before the onset of labor. Cortisol acts on the placenta to stimulate the production of prostaglandins, which are hormone-like substances that have various effects on the uterus.

Prostaglandins help to soften and ripen the cervix, making it more elastic and allowing it to dilate during labor. They also promote contractions by increasing the sensitivity of the smooth muscle cells in the uterine wall to the hormone oxytocin. Oxytocin is another hormone that plays a crucial role in parturition. It is produced by the mother's pituitary gland and acts on the uterus to initiate and maintain uterine contractions.

The fetal hormones, particularly cortisol, also interact with the mother's hormones, such as estrogen and progesterone. Throughout pregnancy, high levels of progesterone by the placenta maintain uterine quiescence and prevent premature contractions. As the levels of cortisol increase, they reduce the sensitivity of the uterine muscle cells to progesterone, allowing the progesterone levels to decrease. This decrease in progesterone, coupled with the increasing levels of estrogen as pregnancy advances, leads to an increase in uterine contractions and the onset of labor.

In summary, the effect of fetal hormones, particularly cortisol, on the uterus causes parturition by promoting the production of prostaglandins, softening the cervix, increasing the sensitivity of uterine muscle cells to oxytocin, and interacting with the mother's hormones to reduce progesterone levels and increase estrogen levels. These hormonal changes ultimately lead to the initiation and progression of labor.