Breastfeeding & your baby:
Breastfeeding protects your baby from a long list of illnesses
Numerous studies from around the world have shown that stomach viruses, lower respiratory illnesses, ear infections, and meningitis occur less often in breastfed babies and are less severe when they do happen. Exclusive breastfeeding (meaning no solid food, formula, or water) for at least six months seems to offer the most protection.
One large study showed that children who are breastfed have a 20 percent lower risk of dying between the ages of 28 days and 1 year than children who weren't breastfed, with longer breastfeeding associated with lower risk.
The main immune factor at work here is a substance called secretory immunoglobulin A (IgA) that's present in large amounts in colostrum, the first milk your body produces for your baby. (Secretory IgA is present in lower concentrations in mature breast milk.) The substance guards against invading germs by forming a protective layer on the mucous membranes in your baby's intestines, nose, and throat.
Your breast milk is specifically tailored to your baby. Your body responds to pathogens (virus and bacteria) that are in your body and makes secretory IgA that's specific to those pathogens, creating protection for your baby based on whatever you're exposed to.
Breastfeeding's protection against illness lasts beyond your baby's breastfeeding stage, too. Studies have shown that breastfeeding can reduce a child's risk of developing certain childhood cancers. Scientists don't know exactly how breast milk reduces the risk, but they think antibodies in breast milk may give a baby's immune system a boost.
Breastfeeding may also help children avoid a host of diseases that strike later in life, such as type 1 and type 2 diabetes, high cholesterol, and inflammatory bowel disease. In fact, preemies given breast milk as babies are less likely to have high blood pressure by the time they're teenagers.
For babies who aren't breastfed, researchers have documented a link between lack of breastfeeding and later development of Crohn's disease and ulcerative colitis.
Breastfeeding & you:
Breastfeeding may reduce your risk of some types of cancer.
Numerous studies have found that the longer women breastfeed, the more they're protected against breast and ovarian cancer. For breast cancer, nursing for at least a year appears to have the most protective effect.
It's not entirely clear how breastfeeding helps, but it may have to do with the structural changes in breast tissue caused by breastfeeding and the fact that lactation suppresses the amount of estrogen your body produces. Researchers think the effect on ovarian cancer may be related to estrogen suppression as well.