Located beneath the skin and above the pectoral muscle, the mammary glands produce milk for a suckling baby following childbirth.

Each gland consists of a series of lobules, small lobes that produce milk. Tubes known as ductal lobes carry the milk to the lactiferous ducts, which open on the nipple. Tiny holes in the nipple secrete the milk. Fat tissue in the breast surrounds the ducts and glands to protect them.

The mammary glands begin developing during puberty, but they don’t become functional until after a woman has given birth. During puberty and especially during pregnancy, several hormones play key roles in the development of the mammary glands:

• Estrogen: This is the key sexual hormone for women; it causes the growth, development, and branching of the duct system. Estrogen also dictates the accumulation of fat in the breast.
• Progesterone: This hormone develops the tissue that will become the mammary glands.
• Prolactin: This hormone dictates the beginning of milk production for each feeding.

Milk production typically begins immediately after childbirth and can continue for years if a child continues to suckle. However, some women experience problems breast-feeding for several reasons. Some of them include:

• Emotional problems such as depression
• Mammary gland abnormalities
• Injuries to the breast
• Inflammation of the breast caused by infection, also known as mastitis
• Anemia
• Malnutrition

Breast-feeding a newborn is a popular topic among mothers. Many who choose not to breast-feed cite the time involved in feeding—six to eight times a day—and the dietary restrictions on the mother as core reasons not to do so. However, proponents of breast-feeding often cite these reasons why mothers should breast-feed:

• Breast milk is easy for the baby to digest and provides balanced nutrition.
• Mothers pass important antibodies to their babies through milk.
• Breast milk is less expensive than formulas.
• Breast-feeding triggers the release hormones that signal the uterus to return to its normal size.
• Breast-feeding can help the mother lose weight.

No matter what decision a mother makes, in most cases her body is prepared to nourish her child; a newborn can survive on breast milk alone for the first six months of life, and sometimes longer.