Influence of body mass index on pregnancy outcomes among HIV-infected and HIV-uninfected Zambian women

OBJECTIVES: To determine the influence of body mass index (BMI) on pregnancy outcomes of HIV-infected and HIV-uninfected Zambian women and to assess the possible role of BMI on mother-to-child transmission rate of HIV. METHODS: We analysed data from a clinical trial on nevirapine administration for the prevention of mother-to-child transmission of HIV in Lusaka, Zambia. Demographic characteristics, medical information and pregnancy outcomes were used in this secondary analysis. RESULTS: A total of 1211 women were included in this analysis and 36% were HIV-infected. Among HIV-infected women, maternal parity and prior stillbirths increased with increasing BMI in univariate analysis. Mean birth weight rose as well at 28.3 g 95% confidence interval (CI)=14.0-42.6] of infant weight per BMI unit. Transmission of HIV from mother to child appeared inversely related to BMI when compared according to BMI quartile (P for trend=0.07). In the HIV-uninfected group, infant birth weight increased with increasing BMI, at 32.7 g (95% CI=23.5-41.9) of infant weight per BMI unit. CONCLUSION: Birth weight increased alongside BMI in both HIV-infected and HIV-uninfected women. There is a suggestion that women with lower BMI have a greater risk of perinatal HIV transmission, even after adjustments for HIV viral load and CD4 count.