Effect of maternal HIV status on infant mortality: evidence from a 9-month follow-up of mothers and their infants in Zimbabwe

OBJECTIVE: To describe infant mortality trends and associated factors among infants born to mothers enrolled in a prevention of mother-to-child transmission (PMTCT) program. STUDY DESIGN: A nested case–control study of human immunodeficiency virus (HIV)-positive and -negative pregnant women enrolled from the national PMTCT program at 36 weeks of gestation attending three peri-urban clinics in Zimbabwe offering maternal and child health care. Mother–infant pairs were followed up from delivery, and at 6 weeks, 4 months and 9 months. RESULTS: A total of 1045 mother and singleton infant pairs, 474 HIV-positive and 571 HIV-negative mothers, delivered 469 and 569 live infants, respectively. Differences in mortality were at 6 weeks and 4 months, RR (95% CI) 9.71 (1.22 to 77.32) and 21.84 (2.93 to 162.98), respectively. Overall, 9-month mortality rates were 150 and 47 per 1000 person-years for infants born to HIV-positive and HIV-negative mothers, respectively. Proportional hazard ratio of mortality for children born to HIV-positive mothers was 3.21 (1.91 to 5.38) when compared with that for children born to HIV-negative mothers. CONCLUSION: Maternal HIV exposure was associated with higher mortality in the first 4 months of life. Infant's HIV status was the strongest predictor of infant mortality. There is a need to screen infants for HIV from delivery and throughout breastfeeding.