Breast milk provides all the calories and nutrients (protein, fat, sugar, vitamins and minerals) that a baby needs for the first 6 months of life. It also contains special proteins made by the mother's immune (infection-fighting) system that help protect babies from illnesses like ear infections (otitis media), lung infections (pneumonia), and vomiting and diarrhea (gastroenteritis). Breastfeeding may also help protect against sudden infant death syndrome.

Breast milk is easier for babies to digest, and breastfed babies tend to spit up less often. Exclusively breastfeeding for the first six months may help prevent food allergies and other medical problems, such as diabetes and obesity. Furthermore, some research suggests that breastfeeding also may help with brain development and learning.

Breastfeeding is convenient, costs less than formula, does not need to be prepared, and is always available at the right temperature. Breastfeeding also requires close physical contact, which helps create a special bond between a mother and her baby and can be especially soothing for babies.

For the mother, the production of breast milk burns extra calories, helps women return to their pre-pregnancy weight more quickly, helps the uterus return to its normal size more quickly after delivery, and may even reduce the risk of ovarian cancer and premenopausal breast cancer.