Effect Of Breast-Feeding On Infant And Child Mortality

Nutrition Research Newsletter, March, 2000

The recognition that HIV is transmitted through breast milk has raised the important question of whether strategies that promote breast-feeding in areas of high HIV prevalence should be changed. Breast-feeding provides important protection against infectious diseases, which account for over two-thirds of the 12 million annual deaths in children younger than five years of age in less-developed countries. Theoretical models have been developed to assess the advantages and disadvantages of breast-feeding for HIV-positive women. According to a recent World Health Organization (WHO) review, these models have an important limitation: The relative risks for mortality associated with lack of breast-feeding were not quantified. Researchers recently conducted a comprehensive pooled analysis of existing studies, examining the effect of not breast-feeding on risk of infant and child mortality due to infectious diseases.

Studies were identified through consultations with experts in international health, and from a Medline search for 1980-1998. A large number of investigators were contacted by WHO, and datasets from those willing and able to participate were included. Using meta-analytical techniques, researchers assessed the protective effect of breast-feeding according to the age and sex of the infant, the cause of death, and the educational status of the mother. All deaths that occurred during the first week of life were excluded, since breast-feeding is unlikely to have had a marked impact on these deaths. Breast-feeding status was assessed before the onset of fatal disease to avoid reverse causality, such as feeding changes due to illness.

Six studies conducted in both urban and rural areas were included in the meta-analysis, providing data on deaths in the second year of life. Most studies included greater than 160 deaths. Acute respiratory infections or diarrhea were the leading cause of death from infectious diseases in three studies. The protection against mortality provided by breastmilk tended to decline with age in all three studies. The protection provided by breast-feeding against all infant deaths was greatest in Pakistan, intermediate in Brazil, and lowest in the Philippines. Protection provided by breast-feeding was slightly greater for girls than for boys. In the first six months of life protection against diarrhea was substantially greater than against acute respiratory infections, but at 6-11 months of age, similar levels of protection were observed against both causes of death. Protection against acute respiratory infections remained constant as the protection against diarrhea declined with age. Lack of breast-feeding was associated with a substantially larger risk in children of poorly educated mothers than in those with more educated mothers.

Infants who are not breast-fed have a six-fold greater risk of dying from infectious diseases in the first two months of life than those who are breast-fed. Protection decreases steadily with age, and is probably due to lower intakes by older children who also receive complementary feeding. The researchers recommend that this data be used in future simulations of the impact of withholding breast-feeding in HIV-positive mothers. The study suggests that it will be difficult, if not impossible, to provide safe breast milk substitutes to children from underprivileged populations. There is wide agreement that the final decision on whether or not to breast-feed when a woman is HIV-positive should reside with the mother and the family.

WHO Collaborative Study Team, Effect of Breast-Feeding on Infant and Child Mortality Due to Infectious Diseases in Less Developed Countries: a Pooled Analysis, The Lancet 355: 451-454 (February 2000) [Correspondence: Prof. Cesar G Victora, Faculdade de Medicina, Universidade Federal de Pelotas, CP 464, 96001-970 Pelotas, RS, Brazil.]