Lactation

Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process can occur with all post-pregnancy female mammals, although it predates mammals. In humans the process of feeding milk is also called breastfeeding or nursing.

In most species, milk comes out of the mother's nipples; however, the monotremes, egg-laying mammals, lack nipples and release milk through ducts in the abdomen. In only one species of mammal, the Dayak fruit bat, is milk production a normal male function.

Galactopoiesis is the maintenance of milk production. This stage requires prolactin. is critical for the milk let-down reflex in response to suckling.

Newborn infants often produce some witch's milk.

Galactorrhea is milk production unrelated to nursing, it can occur in males and females of many mammal species as result of hormonal imbalances or unusual physiological stimuli.

The chief function of lactation is to provide nutrition and immune protection to the young after birth. In almost all mammals, lactation induces a period of infertility, which serves to provide the optimal birth spacing for survival of the offspring.

From the twenty-fourth week of pregnancy (the second and third trimesters), a woman's body produces hormones that stimulate the growth of the milk duct system in the breasts:

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