Impact of infant feeding practices on the risk of mother to child transmission of HIV-1 in Zimbabwe

OBJECTIVE: To determine the magnitude of the contribution of infant feeding practices on the risk of mother to child transmission (MTCT) of the HIV-1 infection. METHODOLOGY: Prospective data from birth until 24 months of age on 236 infants born to HIV-positive mothers in Harare, Zimbabwe was analysed for this study. However, because only a small proportion of infants (2.1%) were HIV-1 polymerase chain reaction (PCR) tested shortly after birth, the PCR results for infants at birth were not incorporated into our analyses. The contribution of infant feeding practices on the risk of MTCT of HIV-1 was assessed using Cox Proportional Hazards Regression Models. RESULTS: The incidence of HIV-1 through MTCT was greatest among breastfed (8.33 per 100 child-months) and mixed fed (8.64 per 100 child-months) infants by 3 months. After adjustment for maternal age, marital status, education and infant antibody HIV-1 status, the cumulative relative risk of MTCT of HIV-1 was 4.19 (95% confidence interval (CI) 3.44, 5.09) among breastfed and 1.10 (95% CI 0.97, 1. 25) among mixed fed infants. The overall MTCT rate of HIV-1 in this study was 40.3%. CONCLUSIONS: Breastfed infants had the greatest cumulative relative risk of MTCT of HIV-1, followed by mixed fed infants, with the highest incidences occurring within the first 3 months.