Maternal biomass smoke exposure and birthweight in Malawi: Analysis of data from the 2010 Malawi Demographic and Health Survey

Background Use of biomass fuels has been shown to contribute to ill health and complications in pregnancy outcomes such as low birthweight, neonatal deaths, and mortality in developing countries. However, there is insufficient evidence of this association in sub-Saharan Africa and Malawi. We therefore investigated effects of exposure to biomass fuels on reduced birthweight in the Malawian population. Methods We conducted a cross-sectional analysis, using secondary data from the 2010 Malawi Demographic and Health Survey, with a total of 9124 respondents. Information on exposure to biomass fuels, birthweight, and size of child at birth, as well as other relevant information on risk factors was obtained through a questionnaire. We used linear regression models for birthweight as a continuous outcome variable and logistic regression for size at birth considered as a dichotomous outcome variable. Models were systematically adjusted for relevant confounding factors. Results Use of high-pollution fuels resulted in a 92 g (95% CI = −320.4 to 136.4) reduction in mean birthweight, compared to low-pollution fuel use, after adjustment for child, maternal, and household characteristics. The fully adjusted OR for risk of having size below average at birth was 1.29 (95% CI = 0.34 to 4.48). Gender and birth order of child were the significant confounding factors in our adjusted models. Conclusions We observed reduced birthweight in children whose mothers used high-pollution fuels, suggesting a negative effect of maternal exposure to biomass fuels on birthweight. However, this reduction was not statistically significant. More carefully designed studies need to be carried out to explore effects of biomass fuels on pregnancy outcomes and health outcomes in general.