Parturition, the process of childbirth, involves a complex neuroendocrine mechanism:
1. Signals arise from the fully formed foetus and placenta cause mild uterine contractions.
2. This is accompanied by an increased estrogen-progesterone ratio and the rise of oxytocin receptors in uterine muscles.
3. The elevated hormone ratio leads to strong contractions of the uterus’s myometrium towards the end of pregnancy.
4. The mature fetus signals uterine contractions by releasing Adrenocorticotropic Hormone (ACTH) from the pituitary and corticosteroid from the adrenal gland.
5. This, in turn, stimulates the mother’s pituitary gland to release oxytocin, acting on her uterine muscles and causing robust contractions, ultimately resulting in the baby’s expulsion from the uterus.