Abstract
Although the protective effect of breastfeeding against infectious diseases has been long suspected, it has only recently been adequately quantified This article reviews the available epidemiologic evidence. Breastfeeding provides marked protection against diarrhoeal morbidity and severity (as measured by its duration, level of dehydration, or case-fatality rate), and mortality. This is true for acute watery diarrhoea as well as for dysentery and persistent diarrhoea. A dose-response pattern is observed: the risk level for children receiving both breastmilk and artificial milk is between that of exclusively breasfed children and that of completely weaned children. Even the introduction of water or herbal teas to a previously exclusively breasfed infant increases the risk of morbidity and mortality. The protection is greatest for young infants, and the period immediately after weaning seems to carry the highest risk. Although breastfeeding does not seem to have an appreciable effect on the incidence of acute respiratory infections as a whole, there is evidence of an effect on the incidence of pneumonia, on the incidence of hospitalization for pneumonia, and on mortality from respiratory infections. The level of protection against pneumonia, however, is lower than that against diarrhoea. Breastfeeding also protects against onus media and other infections, including neonatal sepsis, meningitis, and bacteraemia, although the number of relevant studies is small. A simulation exercise shows that a 40% reduction in the prevalence of nonbreastfeeding would prevent up to 15% of diarrhoea deaths and 7% of pneumonia deaths occurring in regions with a short breastfeeding duration, such as urban Latin America. In regions where breastfeeding durations are longer, the emphasis should be on maintaining these high rates and increasing the proportion of young infants who are exclusively breastfed. The present review confirms that breastfeeding promotion is an essential child survival strategy.