Process of parturition:
A. Fully developed foetus and the placenta gives signals for parturition.
B. Initiation of mild uterine contractions called foetal ejection reflex.
C. Release of oxytocin from the maternal pituitary.
D. Oxytocin causes stronger uterine contractions which further stimulates the secretion of oxytocin.
E. Stimulatory reflex between the uterine contraction and oxytocin secretion continues making the uterine contractions stronger, finally leading to parturition.
F. The placenta is also expelled out of the uterus after parturition.