Lactation is production and secretion of milk to nourish the newborn late in pregnancy. Oxytocin hormone has significant roles in childbirth and lactation. Throughout pregnancy, high concentrations of estrogen and progesterone cause the mother's breasts to enlarge for the preparation for lactation. However this is not the case before childbirth as estrogen and progesterone prevent the action of prolactin, the hormone which stimulates milk production.
