Alcohol and the hormonal control of lactation

Abstract

All mammals produce milk to nourish their young. Milk production (i.e., lactation), which occurs in the mammary glands, is regulated by several hormones, most prominently prolactin and oxytocin. Studies in both humans and laboratory animals have demonstrated that maternal alcohol consumption before and during lactation can interfere with the functions of both of those hormones. Moreover, animal studies found that maternal alcohol consumption during pregnancy and even earlier in the mother's life can impair mammary gland development. Maternal alcohol consumption during pregnancy and lactation also can alter the milk's nutrient composition and result in suckling deficits of the offspring. Alcohol (and possibly its breakdown products) can pass from the maternal circulation into the breast milk. The effects of these substances on the infant, however, are still unknown.

Figure 1

Structure of the female breast and mammary glands. The milk-secreting cells form ball-shaped structures, the alveoli, which are covered on the outside by myoepithelial cells. Several alveoli combine to form a lobule, although a lobule may contain as little as one alveolus and its duct (i.e., the lobular duct). Several lobules form a lobe. The ducts of the lobes (i.e., lactiferous ducts) converge at the nipple. SOURCE: Adapted from Cunningham, F.G.; MacDonald, P.C.; Gant, N.F.; Leveno, K.J.; and Gilstrap, L.C., III (eds.). Williams Obstetrics. 19th ed. Norwalk, CT: Appleton and Lange, 1993.

Figure 2

Development of the female breast and mammary glands: (A) during infancy, (B) before puberty, (C) after puberty, (D) during pregnancy, and (E) during lactation. SOURCE: Adapted from Lawrence, R.A. Breastfeeding: A Guide for the Medical Profession. St. Louis: Mosby, 1994.