Trends in birth weight and gestational age for infants born to HIV-infected, antiretroviral treatment-naive women in Malawi.

Background: We analyzed birth outcomes among infants of treatment-naive, HIV-infected women from a series of mother-to-child transmission of HIV studies in Blantyre, Malawi. Methods: Data from 6 prospective studies at 1 research site were analyzed. Mean birth weight (BW) and gestational age (GA), and frequency of low birth weight (LBW; <2500 g) and preterm (PT) birth (GA <37 weeks) were estimated. We assessed risk factors for LBW and PT birth using mixed-effects logistic regression. Adjusted odds ratios (AOR) and 95% confidence intervals from earlier studies (1989-1994) and later studies (2000-2007) are presented separately. Results: The analysis included 8874 HIV-exposed infants. Mean BW and GA ranged from 2793 to 3079 g, and from 37.8 to 39.0 weeks. Greater maternal age was consistently (during both the early and late periods) associated with lower odds of LBW and PT birth; AOR (95% confidence intervals) for both outcomes in the early and late periods, respectively, were 0.98 (0.96-1.00) and 0.97 (0.95-0.99). Female infant gender was consistently associated with higher odds of PT birth during both periods and with higher odds of LBW during the later period. During the early period, higher maternal education was associated with lower odds of LBW (AOR 0.67 [0.48-0.95]) and PT birth (AOR 0.70 [0.51-0.95]), and later birth year was associated with lower odds of PT birth (AOR 0.35 [0.19-0.70]). Conclusions: BW and GA remained stable within each time period. This analysis provides important baseline information for monitoring HIV treatment effects on birth outcomes. Modifiable factors affecting BW and GA should continue to be explored.