Timing and determinants of mother-to-child transmission of HIV in Nigeria

Objective: To characterize the timing and determinants of mother-to-child transmission (MTCT) of HIV among mothers receiving single-dose nevirapine to prevent MTCT in Nigeria. Methods: Three hundred and seventy-one HIV-infected mothers and their infants were followed from birth, at 1 week, and at 1, 3, 6, and 12 months. Risks of in utero (IU), intrapartum (IP/EPP), and postnatal (PP) transmission were quantified using conditional Cox regressions. Results: Maternal viral load was the only risk factor for IU transmission after controlling for known risk factors. Low birth weight, premature birth, mixed feeding, and maternal viral load were associated with IP/EPP transmission. Increased PP transmission was associated with low birth weight and mixed feeding. At 6 months, mixed-fed infants were more likely to acquire infection than formula-fed infants (hazard ratio = 5.74; 95% CI, 1.26-26.2). Conclusion: Risk factors for IU transmission differed from those of IP and PP transmission. Reducing mixed feeding and low birth weight delivery among HIV-infected mothers can further decrease IP and PP transmission. © 2009 International Federation of Gynecology and Obstetrics.