The association between maternal exposure to air pollutants and birth defects in China: A population-based cohort study

This study was to investigate the association between trimester-specific exposure to air pollutants and the risk of Birth defects (BDs) among Chinese births. A time-dependent Cox proportional hazards model was used to explore the associations between trimester-specific and entire pregnancy concentrations of the pollutants and BDs at Changsha, China from 2014 to 2018. Each increment in ambient particles with diameters of 2.5 ?m or less (PM2.5) concentrations was associated with a higher risk of BDs with an hazards ratios (HR) [95% confidence intervals (CI)] between 1.06 (1.03?1.09) and 1.39 (1.27?1.53) during the entire pregnancy period. This association was also pronounced for ozone (O3) with an HR (95% CI) between 1.03 (1.00?1.06) and 1.23 (1.15?1.31) over the entire pregnancy. Elevated risks of BDs were found to be linked to sulfur dioxide/nitrogen dioxide (SO2/ NO2) exposure during the first trimester, carbon monoxide (CO) exposure during the second trimester, and particulate with diameters of 10 ?m or less (PM10) during the third trimester of pregnancy. For subtype analyses, PM2.5 exposure exhibited a significant association with a variety of BD types, especially nervous system defects with an HR (95% CI) between 1.13 (1.03?1.24) and 1.19 (1.09?1.31), PM10 was associated with complex defects and nervous system defects, O3/SO2 was associated with all types of BDs except cardiac defects, NO2 was associated with nervous system defects, and CO was associated with unclassifiable defects. The study adds to evidence on the association between maternal exposure to air pollutants and BDs and has implications for public health policy.

Automated summary

The study explores the association between trimester-specific exposure to air pollutants and the risk of Birth defects (BDs) among Chinese births. The findings suggest that exposure to PM2.5 and O3 during pregnancy is associated with increased risks of BDs, with different pollutants during different trimesters showing links to different BD types. These results provide valuable insights for public health policy.