Determinants of low birth weight among HIV-infected pregnant women in Tanzania

Background: Low birth weight (LBW) increases the risk of infant death, but little is known about its causes among HIV-infected populations in sub-Saha ran Africa. Objective: We assessed sociodemographic, nutritional, immunologic, parasiti c, and infant risk factors for birth weight, LBW, and V small-for-gestation al-age (SGA) status in a cohort of 822 HIV-positive women enrolled in a cli nical trial of vitamin supplementation and pregnancy outcomes in Dar es Sal aam, Tanzania. Design: Women were enrolled at prenatal care clinics during their second tr imester, at which time blood, stool, urine, and genital specimens were coll ected, and anthropometric measurements and sociodemographic data were recor ded. Birth weight was measured at hospital delivery. Results: The mean (+/- SD) birth weight was 3015 +/- 508 g, 11.1 % of newbo rns weighed < 2500 g (LBW), and 11.5% were SGA. In multivariate analyses, m aternal weight at enrollment and a low CD8 cell count were inversely associ ated with LBW. Advanced stage HIV disease, previous history of preterm birt h, Plasmodium falciparum malaria, and any helmintic infection were associat ed with hi-her risk of LBW. The intestinal parasites Entamoeba histolytica and Strongyloides stercoralis were predictors of LBW despite their low prev alence in the cohort. In a multivariate-adjusted linear regression model, B MI, midupper arm circumference, a CD4 cell count < 200 X 10(6) cells/L (200 cells/mm(3)), primiparity, maternal literacy, and infant HIV infection at birth were significantly associated with birth weight in addition to risk f actors included in the LBW model. Determinants of SGA included maternal wei ght, low serum vitamin E concentration, candidiasis, malaria, and infant HI V infection at birth. Conclusion: Prevention of HIV disease progression and vertical transmission , improved nutritional status, and better management of malaria and intesti nal parasitic infections are likely to reduce the incidence of LBW in Tanza nia.