Breastmilk contains leukocytes, specific antibodies, and other antimicrobial factors that protect the infant against many common infections. Breastfed infants at high risk for allergic symptoms such as eczema and asthma show reduced incidence and severity of these symptoms. Breastmilk enhances cognitive and emotional development. Return to prepregancy state is quicker. Incidence of obesity in later life is reduced.
Some women gain self-esteem, greater maturity and improved parenting skills.
In the United States very few situations definitively contraindicate breastfeeding. There are no nutritional contraindications except in rare situations where the infant has intestinal lactase deficiency, galactosemia, or phenylketonuria. A less than perfect maternal diet is not a reason to avoid breastfeeding. HIV can be transmitted in breastmilk and, in the U.S., is a contraindication for breastfeeding. In contrast to developing nations, in the U.S. the benefits of breastfeeding do not outweigh the hazard.