Lactation: 
The term lactation refers to production of milk. The period after giving birth during which milk is secreted in the breasts of woman. The first secretion from the breast occuring shortly after childbirth is called colostrum. It is rich in calories and protein. Also, it contains antibodies that provide passive immunity for the newborn baby.

Three or four days after deliverly, the breasts begins to secrete milk. Its synthesis is stimulated by the pituitary hormone prolactin. Its release is stimulated by a rise in the level of oxytocin when the baby begins nursing. Milk contains inhibitory peptide. If the breasts are not fully emptied, the peptide accumulates and inhibits milk production. This autocrine action, thus, matches supply with demand.