Your breasts are not just bigger these days--they're busy making milk, too.
Up until now it may have been possible to think of your breasts as you always have, as a sexy part of your body that gives you and your partner sensual pleasure. Now it's becoming increasingly clear that your breasts have a wonderful function as well as a lovely form: They were designed to nourish your children.
Your breasts are a generous cup size larger than at the start of your pregnancy, and your nipples may have become so sensitive recently that it's painful to pull on clothing or to feel them rub against your terry cloth robe. These are all signs that your body is preparing to nurse your baby, whether you plan to or not.
Each breast has about 20-25 branching segments, called "lobes," that separate bunches of fat, connective tissue, nerves, and lymph vessels. Inside each lobe are alveoli that produce milk in response to hormones and your baby's sucking action on the nipple. It's a well-orchestrated supply-and-demand system in which the more your baby signals your breasts to produce milk, the more milk your body makes.
You may have noticed a yellowish fluid, slightly thicker than milk, already coming out of your nipples. This is colostrum--your baby's first food. Rich in fat and high in protein and antibodies, colostrum is one more example of nature's perfect design. Its nutritional content helps your baby gain weight fast, excrete his first body waste, and fight infection from the very first minutes of life.
Originally published in You & Your Baby: Pregnancy.
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