Cooking stoves and risk of birth defects in urban China.

INTRODUCTION: Birth defects are a leading cause of infant death. Pregnant women spend a large amount of time indoors, and little research from population-based studies has investigated the association between indoor air pollution and birth defects. We aimed to examine whether using coal, biomass, or electromagnetic stoves for cooking is associated with risk of birth defects compared to using gas stoves. METHODS: A birth cohort study was conducted from 2010 to 2012 in Lanzhou, China. Cases (n = 264) were singleton births with birth defects, which were defined as abnormalities of structure or function, including metabolism, presented at birth based on the International Classification of Diseases (ICD)-10 codes. Controls (n = 9926) were defined as singleton live births without birth defects. Unconditional logistic regression models were employed to estimate the association adjusting for confounding variables. RESULTS: Compared to gas stoves for cooking, biomass (OR = 2.66, 95%CI: 1.38-5.13), and electromagnetic stove (OR = 1.90, 95%CI: 1.26-2.88) for cooking were associated with an increased risk of birth defects. The significant associations remained among non-congenital heart disease (CHD) defects but not CHDs. CONCLUSIONS: Using biomass or electromagnetic stoves for cooking during pregnancy was associated with an increased risk of birth defects. Additional studies are warranted to confirm these novel findings. Studies with larger sample size or greater statistical power are also warranted to better estimate the associations for individual birth defects.