Definitions of Common Breastfeeding Terms.

antibody A substance that protects against infection.

areola The circular area of pigmented skin that surrounds the nipple.

colostrum A concentrated fluid secreted by the breast at the end of pregnancy and shortly after childbirth that provides nutrition as well as protection against disease.

engorgement Fullness, swelling, and enlargement of the breasts.

foremilk Low-fat milk that leaves the breast first during breastfeeding or pumping; the longer the time periods between breast drainage, the lower in fat the foremilk becomes.

hindmilk Higher-fat milk that comes later during a breastfeeding or pumping as the breast becomes more fully drained.

hormone A chemical messenger produced in one part of the body that affects another part of the body.

lactation The action of producing and secreting milk.

milk ejection reflex The reflex that causes milk to flow to the nipples and be ejected from the breast (aka let-down, milk release and milk ejection).

oxytocin A hormone produced in the brain, released during labor, nipple stimulation, and at other times (such as during a massage); it causes alveolar contraction, milk release (ejection) and uterine contractions.

progesterone A hormone produced by the placenta in large amounts during pregnancy that stimulates breast development and inhibits production of large volumes of milk.

prolactin A hormone produced in the brain that stimulates breast development and affects milk production.

suck, suckle The baby’s milking action at the breast; in traditional usage, a baby at the breast “sucked” while a mother “suckled.”
