Maternal exposure to biomass smoke and reduced birth weight in Zimbabwe.

PURPOSE To examine the association between household use of biomass fuels for cooking and birth weight. METHODS Analysis is based on 3559 childbirths in the 5 years preceding the 1999 Zimbabwe Demographic and Health Survey. Birth weights, recorded by trained professionals at local health clinics, were derived from health cards at home or from mother's recall. Multiple regression method was used to estimate the effect of household use of biomass cooking fuels (wood, dung, or straw) on birth weight, after controlling for child's sex and birth order, mother's education and nutritional status, pregnancy care, household living standard, and other potentially confounding factors. RESULTS Babies born to mothers cooking with wood, dung, or straw were 175 g lighter (95% CI,-300,-50), on average, compared with babies born to mothers using LPG, natural gas, or electricity. The difference was 120 g (95% CI,-301, 61) for children whose birth weights were taken from health cards, and 183 g (95% CI,-376, 10) for children whose birth weights were reported by mothers. CONCLUSIONS Household use of high pollution cooking fuels may cause reduced birth weight. The relationship needs to be further investigated using more direct measures of smoke exposure and birth weight and accounting for environmental tobacco smoke.