Method of
feeding and transmission of HIV-1 from mothers to children by
15 months of age: prospective cohort study from Durban, South Africa
Coutsoudis A. et al. AIDS, 15:379-387, 2001
This is a follow-up study of Anna Coutsoudis’ previous work on the reduced risk of transmission when infants are exclusively breastfed. The previous South African study followed exclusively breastfed infants for the first three months of age; these results report on breastfeeding practices and transmission outcomes for children followed to 15 months of age as part of a randomized trial of vitamin A supplementation of pregnant women. A total of 551 HIV-1 positive pregnant women enrolled in this prospective study. After counseling on feeding choices, the women self-selected to either formula feed or to breastfeed. Those who chose to breastfeed, were supported to exclusively breastfeed for three months or more. Three groups were compared for HIV-1 transmission: 157 formula fed; 118 exclusively breastfed for three months or longer; 276 mixed-fed formula and breastmilk. They did not differ in risk factors for transmission. To determine transmission risk, cumulative probabilities of detecting HIV over time were estimated using the Kaplan-Meier methods.
Results showed that probabilities of HIV detection remained the same at 19.4%, among those who never breastfed and those who exclusively breastfed for up to six months. Those who were mixed fed showed greater probability of 26.1%. At 15 months the likelihood of HIV infection remained lower (24.7% compared to 35.9%) for those who exclusively breastfed for three months or longer when compared to other feeding patterns.
The study concluded that those at greatest risk for infection were on a mixed feeding regimen. The authors note that exclusive breastfeeding has no added risk for mother to child transmission for HIV-1. Moreover they note that exclusive breastfeeding remains infrequently practised even though it confers additional benefits over mixed and formula feeding such as the reduced risk of diarrheal disease, respiratory illness and allergy.
The mechanisms through which exclusive breastfeeding may be safer than mixed feeding are not known. However, the researchers “favour the hypothesis that contaminated fluids and foods introduced in mixed breastfed babies damage the bowel and facilitate entry into the tissues of HIV in breastmilk.” A study in Guatemala showed that gut damage was greatest with mixed feeding and least with exclusive breastfeeding.
