According to the sources, the process of childbirth (parturition) is induced by a complex neuroendocrine mechanism . The signals originate from the fully developed foetus and the placenta, which induce mild uterine contractions known as the foetal ejection reflex . This reflex specifically triggers the release of oxytocin from the maternal pituitary gland . Oxytocin then acts on the uterine muscle to cause stronger contractions, which in turn stimulate further oxytocin secretion in a stimulatory reflex that leads to the expulsion of the baby .