Lactation

Lactation is the production and secretion of milk by the mammary glands, a process that occurs in female mammals after pregnancy and is adapted to provide nourishment for the offspring. In humans, lactation also involves complex hormonal feedback and behavioral cues that coordinate feeding and child development.

Anatomy and physiology: Milk is produced in the alveoli of the breast and stored in lobules connected by ducts. The secretion is stimulated by prolactin, while milk is ejected from the breast by the milk let-down reflex, primarily driven by oxytocin in response to infant suckling or nipple stimulation. Pregnancy prepares glandular tissue; after birth, hormonal changes enable ongoing milk production.

Types of milk and stages: Colostrum is the initial fluid rich in antibodies and nutrients, followed by transitional milk and mature milk. Lactogenesis I occurs during late pregnancy, lactogenesis II after birth as milk “comes in,” and lactogenesis III denotes established lactation.

Benefits and considerations: For infants, breast milk provides ideal nutrition and immune protection and supports growth and development. For mothers, breastfeeding is associated with uterine involution and a reduced risk of certain cancers. Not all people can or choose to breastfeed; alternatives include expressed milk or formula.

Practice and guidelines: Health authorities commonly recommend exclusive breastfeeding for about six months, with continued breastfeeding alongside complementary foods for up to two years or longer as feasible. Lactation can be supported by proper latch, pumping, and storage of expressed milk, as well as professional guidance when needed.