Breast milk is best for your baby, and the benefits of breastfeeding extend well beyond basic nutrition. In addition to containing all the vitamins and nutrients your baby needs in the first six months of life, breast milk is packed with disease-fighting substances that protect your baby from illness.

That's one reason the American Academy of Pediatrics recommends exclusive breastfeeding for the first six months (although any amount of breastfeeding is beneficial) and scientific studies have shown that breastfeeding is good for your health, too.

Some of the most important benefits breastfeeding offers you and 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 happen. Exclusive breastfeeding (meaning no solid food, formula or water) for at least six months seems to offer the most protection.

One large study by the National Institute of Environmental Health Sciences 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.

Breastfeeding's protection against illness lasts beyond your baby's breastfeeding stage. 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 are teenagers.

Breastfeeding can protect your baby from developing allergies

Babies who are fed a formula based on cow's milk or soy tend to have more allergic reactions than breastfed babies.

Scientists think that immune factors help prevent allergic reactions to food by providing a layer of protection to a baby's intestinal tract. Without this protection, inflammation can develop and the wall of the intestine can become "leaky." This allows undigested proteins to cross the gut where they can cause an allergic reaction and other health problems.

Babies who are fed formula rather than breast milk don't get this layer of protection, so they are more vulnerable to inflammation, allergies and other eventual health issues.

Breastfeeding may boost your child's intelligence

Various researchers have found a connection between breastfeeding and cognitive development. In a study of more than 17,000 infants followed from birth to 6 1/2 years, researchers concluded from IQ scores and other intelligence tests that prolonged and exclusive breastfeeding significantly improves cognitive development.

Another study of almost 4,000 children showed that babies who were breastfed had significantly higher scores on a vocabulary test at 5 years of age than children who were not breastfed and the scores were higher the longer they had been nursed.

Preterm infants with extremely low birth weight who received breast milk shortly after birth improved their mental development scores at 18 months when compared with preterm infants who weren't given breast milk. In a later study, researchers found that the higher scores held at 30 months and that the babies who received breast milk were also less likely to be hospitalized again because of respiratory infections.

Experts say that the emotional bonding that takes place during breastfeeding probably contributes to some of the brainpower benefits but that the fatty acids in breast milk may play the biggest role.

Breastfeeding may protect your child from obesity

The American Academy of Pediatrics recommends breastfeeding as a way to help reduce your child's risk of becoming overweight or obese. An analysis of 17 studies published in the American Journal of Epidemiology shows that breastfeeding reduces a child's risk of becoming overweight as a teen or adult.

Experts think that breastfeeding may affect later weight gain for several reasons:

• Breastfed babies are better at eating until their hunger is satisfied, leading to healthier eating patterns as they grow.
• Breast milk contains less insulin than formula. (Insulin stimulates the creation of fat.)
• Breastfed babies have more leptin in their system, a hormone that researchers believe plays a role in regulating appetite and fat.
• Compared with breastfed babies, formula-fed infants gain weight more rapidly in the first weeks of life. This rapid weight gain is associated with later obesity.

Breastfeeding may lower your baby's risk of SIDS

A large German study published in 2009 found that breastfeeding – either exclusively or partially – is associated with a lower risk of sudden infant death syndrome (SIDS). The researchers concluded that exclusive breastfeeding at 1 month of age cut the risk of SIDS in half.

The U.S. Centers for Disease Control and Prevention (CDC) recommends breastfeeding for as long as possible to reduce the risk of SIDS.

Breastfeeding can reduce your stress level and your risk of postpartum depression

The National Institutes of Health reviewed more than 9,000 study abstracts and concluded that women who didn't breastfeed or who stopped breastfeeding early on had a higher risk of postpartum depression.

Many women report feeling relaxed while breastfeeding. That's because nursing triggers the release of the hormone oxytocin. Numerous studies in animals and humans have found that oxytocin promotes nurturing and relaxation. (Oxytocin released while nursing also helps your uterus contract after birth, resulting in less postpartum bleeding.)

One study found that women who had high amounts of oxytocin in their system (50 percent of breastfeeding moms as opposed to 8 percent of bottle-feeding moms) had lower blood pressure after being asked to talk about a stressful personal problem.

By the way, if you're being treated for depression, you can still breastfeed your baby. Your healthcare practitioner can help you identify safe ways to treat your depression while nursing.

Breastfeeding may reduce your risk of some types of cancer

Numerous studies have found that the longer women breastfeed, the more they are protected against breast and ovarian cancer. For breast cancer, nursing for at least a year appears to have the most protective effect.

It is 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.