What is Lactation?
High levels of estrogens and progesterone during pregnancy stimulate the breasts to develop prior to lactation, or milk production. At the same time, levels of the hormone prolactin increase. Estrogen and progesterone inhibit milk production.
Around the time of birth, the breasts secrete small amounts of a fluid called colostrum. At childbirth, estogen and progestone levels fall and milk is produced. When the baby suckles, oxytocin is released from the pituitary, stimulating the muscles surrounding the milk-producing cells, and milk is released.