Association between low birth weight and infant mortality in children born to human immunodeficiency virus 1-infected mothers in Tanzania

Background: The relationship between low birth weight and infant mortality among children born to human immunodeficiency virus (HIV)-infected mothers has not been thoroughly investigated. Methods: A total of 1078 HIV-infected pregnant women in Tanzania were followed up until delivery and with their infants thereafter. The babies' HIV status was assessed at birth, 6 weeks and every 3 months thereafter. Using Cox proportional hazards models, we estimated the associations of low birth weight with neonatal, postneonatal and infant mortality and further examined whether the association between low birth weight and mortality was modified by pediatric HIV infection. Results: Among 823 singletons, low birth weight was strongly related to neonatal mortality (relative risk, 5.14; 95% confidence interval, 2.32-11.39). The association with postneonatal mortality was modified by child's HIV status. Among infants who were either negative or indeterminate at 6 weeks of age, low birth weight was associated with a 3-fold increased risk of mortality (relative risk, 3.16; 95% confidence interval, 1.36-7.37). In the positive infants, however, the association was no longer significant. Conclusions: Although the importance of preventing HIV transmission cannot be overemphasized, efforts to reduce the incidence of low birth weight would enhance the benefit of preventing HIV transmission. Even in populations with no access to antiretroviral treatments, interventions to reduce the incidence of low birth weight would result in a significant reduction in infant mortality.