Social inequality influences the impact of household air pollution on birth outcomes

Studies demonstrated associations between maternal exposure to household air pollution from cooking and increased risk of adverse birth outcomes in offspring; however, the modifying effect of socioeconomic status (SES) on this association has not been explored. In a cohort of pregnant women with 800 single live births between 2016 and 2017 in rural and semi urban areas of Bangladesh, we tested the hypotheses that kitchen location and cooking fuel type affect birth outcomes (birth weight, low birth weight [LBW] and small for gestational age [SGA]) and these associations vary by SES. Demographic characteristics including SES, kitchen location and fuel type were assessed in prenatal visits. Neonatal anthropometric measurements were recorded within 72 h of births. We performed multivariable linear and logistic regressions adjusting for potential confounders to test the study hypotheses. For newborns from households with indoor kitchens, adjusted mean birth weight was 65.13 g (95% confidence interval [CI]: −118.37, −11.90) lower and the odds of LBW and SGA were 58% (odds ratio [OR]:1.58, 95% CI: 1.12, 2.24) and 41% (OR: 1.41, 95% CI: 1.05, 1.92) higher compared to those born in households with outdoor kitchens. We found SES significantly modified the associations between kitchen location and birth outcomes in households using biomass fuels. Newborns from low SES households with indoor kitchens had 89 g lower birth weight and a higher odds of being born with LBW (OR: 2.08, 95% CI 1.23, 3.58), and SGA (OR: 1.70, 95% CI 1.06, 2.76) than those born in high SES households using outdoor kitchens. In areas with poor access or affordability to clean fuel such as in our study population, cooking in an outdoor kitchen can reduce the burden of LBW and SGA, particularly for low SES households. Promoting outdoor kitchens is a possible intervention strategy to mitigate adverse birth outcomes. [Display omitted] •Indoor cooking increased the odds of low birth weight and small for gestational age.•Low Socioeconomic status associated with low birth weight.•Socioeconomic status modified the effect of kitchen location on birth outcomes.