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Your Amazing Breasts

For a woman's breasts, pregnancy marks the role of a lifetime. As soon as they get the hormonal signal that this month's egg has been fertilized and implanted in the uterus, those amazing mammary glands start cooking. Almost before you know it, they grow by leaps, bounds, and cup sizes on the outside, while furiously developing a milk production network on the inside. After all, pregnancy -- or its culmination, a tiny mouth to feed -- is what women's breasts have been waiting for since puberty. Here's an insider's guide to what's happening and what you can do about the aches, pains, drips, and droops that can affect pregnant breasts from conception to mission accomplished.


What's happening: Each month when a woman ovulates, estrogen and progesterone levels in her blood rise, prompting the uterus to become a soft, spongy, nurturing nest. The same hormonal duo also clues the framework of milk-making tissue that pregnancy may be imminent, causing breasts to swell and tingle. If conception doesn't occur, breasts usually wane in size and sensitivity with the approach of menstruation.

But when sperm and egg unite and an embryo starts to grow in the uterus, estrogen and progesterone output surges. For breasts, it's off to the races. The milk production and delivery system begins to flourish immediately.

Signs and symptoms: Though hardly noticeable outwardly, all that interior activity is quickly felt. Many women report that heavy, sore, tingly breasts are the first clue they're pregnant -- even before a missed period. "They say it's like premenstrual pain but more intense," says Harold Miller, M.D., assistant professor of obstetrics and gynecology at Baylor College of Medicine in Houston.

What to do: Nothing, other than testing to see if you're pregnant. Cool compresses may relieve breast tenderness.


What's happening: Increasing estrogen causes the milk ducts to lengthen and branch out, while rising progesterone levels promote the growth of the alveoli, grape-like clusters of glandular tissue where milk is made later on. Blood flow to the breasts steps up, too, and fatty tissue builds up to surround and cushion the expanding network of milk ducts and glands.

Signs and symptoms: Nipples become more erect and more sensitive. The areola, the pigmented circle around each nipple, enlarges and darkens, so that in about eight months it will offer a good target for a hungry infant. Montgomery's glands, a ring of small bumps on the areola that secrete an antibacterial substance, grow more prominent. Overall breast size increases, sometimes dramatically. Veins may be noticeable on the surface. Feelings of tenderness, heaviness, and fullness may continue.

What to do: Time for a super-strength bra. Each breast grows an average of two pounds during pregnancy. "You need to continue to get well-fitted bras as you grow," says Chris Auer, a certified lactation consultant at the University of Cincinnati. Don't buy too big to allow for growth or stick with a bra that's too small and constricts developing tissue. Ideally, have your bras fitted by a professional at a lingerie store. Each bra will cost about $20 to $30, but the money's worth it for comfort and support.


What's happening: Driven by still escalating hormones, the visible changes that began earlier become even more marked: The ducts and alveoli continue to develop, and blood supply increases to support that expansion. The hormone prolactin, produced by the pituitary gland in the brain, causes cells in the alveoli to differentiate so that later they can produce milk (synthesized from blood). These cells, called acini cells, don't kick in to production mode before birth. By trimester's end, however, breasts contain colostrum, a fluid rich in protein, fat, vitamins, minerals, and antibodies that will make up your baby's first meals.

Signs and symptoms: The darkening areola, the prominence of Montgomery's glands, breast growth, and surface veins become more obvious. With estrogen levels rising throughout pregnancy, nipple sensitivity also may increase. As breasts enlarge, stretch marks -- striae gravidarum -- may appear on the skin. Clear, straw-colored colostrum may leak, though that's more common later.

And if your breasts don't quite fit this pattern? Don't worry. "All the breast changes are part of a continuum," says Erol Amon, M.D., an obstetrician/gynecologist at Saint Mary's Health Center, in St. Louis. "Symptoms overlap, and it's very individual what happens and when."

What to do: If hot water causes colostrum to leak in the shower or you wake up with some crusty discharge, avoid soaping and scrubbing, which are uncomfortable, drying, and unnecessary (Montgomery's glands do enough cleaning). Instead, daub the nipple with a warm-water compress to clean off the leakage, and pat or air dry.

If your bra feels tight, replace it -- for present comfort as well as future appearance: When the Cooper's ligaments that support the breasts stretch, they never return to their previous tautness. A supportive bra will minimize the gravitational drag of enlarged breasts on those ligaments. If you exercise vigorously -- running, taking aerobics classes -- and find your heavier breasts bouncing uncomfortably, invest in a well-constructed, nonbinding sports bra. Consider changing to a form of exercise that involves less jarring motion, such as swimming, walking, or using a treadmill or exercise bike.


What's happening: The milk production and delivery system continues to proliferate. By the end of pregnancy, each breast has 15 to 20 lobes, each consisting of a major branch of the alveoli on the interior end and a milk duct that narrows to an opening in the nipple on the exterior. Each of those lobes, in turn, branches inward into 20 to 40 lobules, smaller milk ducts with 10 to 100 supporting alveoli or milk sacs.

At this point, the breasts are capable of producing milk should a baby be born early -- but only if that happens. Without stimulation from a sucking infant or pump, milk production is on hold, thanks to the inhibiting effects of estrogen and progesterone on prolactin, which prompts milk-making cells into action.

Signs and symptoms: With intensified growth, all the other signature changes in appearance and sensation become even more evident. Colostrum is now more likely to leak from breasts.

What to do: If you plan to breastfeed, make sure your nipples will protrude enough for a baby to get hold of: With finger and thumb at noon and six o'clock on the areola at the base of the nipple, gently press down toward the wall of the chest. (Don't squeeze your thumb and finger together, or the nipple may invert further.) The nipple should pop out. If it turns inward, talk to your health-care provider, who may recommend you sparingly massage your nipples. A breast shield, a dome-shaped plastic shield with air-flow holes, may also have to be worn when feeding to help the baby latch on.

Now is the time to take a breastfeeding class, offered by hospitals and childbirth education associations. Such instruction provides more information than the short segment on nursing included in childbirth classes, says Auer.

If you're leaking a lot, consider wearing a properly fitted nursing bra with washable pads.


What's happening: When the baby is born and the placenta delivered, estrogen and progesterone levels plummet. Now free of the inhibiting pregnancy hormones, the prolactin that's being produced by the pituitary gland can finally let the acini cells in the alveoli know that it's time to make milk. Milk usually forms within two to three days after delivery. In the meantime, breasts produce colostrum.

Signs and symptoms: Right after childbirth, women don't usually notice any difference in their breasts. Even when a newborn begins sucking out the precious colostrum, there isn't a distinctive sensation of milk flow. But when the milk supply does come in, it can be quite dramatic. The breasts seem flooded with milk and may become engorged or hard and uncomfortable.

What to do: If you're going to breastfeed, start trying within an hour of delivery, if possible, and then nurse every two to three hours or as often as the baby demands. "Putting the baby to breast often, right from the start, can prevent engorgement," says nurse-midwife Angela Deneris, who teaches at the University of Utah College of Nursing. It will also accustom the baby to nursing, provide her with the nourishing and immunizing benefits of colostrum, and establish a routine of regularly and frequently draining the breasts¿ -- a key to ample milk production.

If you don't intend to nurse, the milk-making process is easily discouraged. Not emptying the breasts of the initial milk supply compresses the milk-making structure and prevents more production. Wearing a snug-fitting bra, a tightly wrapped towel, or a compression bandage further hampers incoming milk, which is absorbed by surrounding tissues. You may still experience some soreness and engorgement. Applying an ice-pack or cool compress for 10 or 15 minutes every hour, as well as taking a mild pain reliever, such as acetaminophen, may give some relief.


What's happening: A hungry infant is just the customer your breasts have been waiting for. The sucking not only draws out the colostrum but also sends a message to the pituitary gland that milk is needed. The pituitary gland then produces oxytocin, the hormone that stimulated the uterus to contract during labor and now causes the tiny muscles lining the alveoli to contract and squirt out milk. This is known as the milk ejection reflex, or letdown. At the same time, the pituitary sends out a new burst of prolactin, signaling the cells of the alveoli to produce more milk to replace what's being consumed.

When letdown occurs, milk is propelled from the many milk sacs in the interior of the breast to enlarged portions of the milk ducts called lactiferous sinuses, just beneath the areola. When the baby latches on to the breast, her gums put pressure on the sinuses and milk is expelled up the duct and out the mother's nipple pores.

Signs and symptoms: Latch-on can be uncomfortable for 30 seconds or so, until milk begins to flow, the baby's tongue moves, and she swallows. Other than that, nursing mothers shouldn't feel pain during breastfeeding. More discomfort could be a sign of improper attachment, engorgement, or an infection of the nipple or breast.

"On a ten-point scale of how much it hurts, anything that goes beyond a four suggests something's wrong," says nurse-midwife Deneris.

Very often, the baby isn't taking enough breast into her mouth and is sucking on the nipple instead of the areola. Engorgement, brought on by a missed feeding or waiting too long between nursing sessions can cause problems as well: It can flatten the nipples and areolae, temporarily hampering latch-on.

Nipple irritation and a burning sensation could be a sign of candidiasis, or thrush, a fungal infection common in infants that can be transmitted to mother's nipples. A tender, reddened area of the breast along with flu-like symptoms (fever, chills, general achiness) suggests mastitis, a more serious infection of breast tissue.

What to do: For nipple pain, check positioning. Make sure the baby is pulled in close to your breast, with her mouth wide open and your nipple well behind her gums. Between feedings, try soothing soreness by expressing a small amount of milk and allowing it to air dry on the nipple, applying a lanolin-based nipple cream, or using warm, moist compresses -- found to be the best pain reliever in a recent study of 177 new mothers.

To ease engorgement, apply moist, warm compresses to the breast three to five minutes before feeding. Then express enough milk to soften the areola and make latching-on easier. Use a cool compress after feeding. Nurse frequently -- every two to three hours.

The symptoms of nipple thrush and mastitis can be easily confused. What's more, the treatment for mastitis, prescription antibiotics, can actually worsen candidiasis (which usually responds quickly to over-the-counter antifungal medication). Get an in-person diagnosis from your doctor if you suspect either one.


What's happening: Weaning quickly cuts off the milk-making process. If the milk isn't consumed, the factory shuts down. Existing milk is absorbed, and without hormonal stimulus no more is manufactured. Ducts, alveoli, fat, and extra blood vessels contract.

Signs and symptoms: The stretched skin surrounding the vast lactation network contracts somewhat but not completely, likely leaving a looser, more teardrop-shaped breast than before pregnancy. On the positive side, nursing decreases a woman's risk of breast cancer later in life.

What to do: Count your blessings, even if they're two fewer than before. "A lot of women are surprised and disappointed to find that when pregnancy and nursing are all over they have smaller or different-shaped breasts than before," says Jacqueline Shannon, who wrote The New Mother's Body Book to help women understand the postbaby body. "But most are philosophical about it. For instance, I look at the trade-off. I can't imagine life without my wonderful daughter. I'd happily lose a cup size for her."

Contributing editor Anne Reeks reviews software for Parenting and writes frequently on other topics.