Method of feeding and transmission of HIV-1 from mothers to children by 15months of age: prospective cohort study from Durban, South Africa

Objective: To determine the risk of HIV transmission by infant feeding moda lity. Design and setting: A prospective study in two hospitals in Durban, South A frica. Participants: A total of 551 HIV-infected pregnant women enrolled in a rand omized trial of vitamin A. Interventions: Women self-selected to breastfeed or formula feed after bein g counselled. Breastfeeders were encouraged to practice exclusive breastfee ding for 3-6 months. Main outcome measures: Cumulative probabilities of detecting HIV over time were estimated using Kaplan-Meier methods and were compared in three groups : 157 formula-fed (never breastfed); 118 exclusively breastfed for 3 months or more; and 276 mixed breastfed. Results: The three feeding groups did not differ in any risk factors for tr ansmission, and the probability of detecting HIV at birth was similar. Cumu lative probabilities of HIV detection remained similar among never and excl usive breastfeeders up to 6 months: 0.194 (95% Cl 0.136-0.260) and 0.194 (9 5% Cl 0.125-0.274), respectively, whereas the probabilities among mixed bre astfeeders soon surpassed both groups reaching 0.261 (95% Cl 0.205-0.319) b y 6 months. By 15 months, the cumulative probability of HIV infection remai ned lower among those who exclusively breastfed for 3 months or more than a mong other breastfeeders (0.247 versus 0.359). Conclusion: Infants exclusively breastfed for 3 months or more had no exces s risk of HIV infection over 6 months than those never breastfed. These fin dings, if confirmed elsewhere, can influence public health policies on feed ing choices available to HIV-infected mothers in developing countries. (C) 2001 Lippincott Williams & Wilkins.