Insights from over a million births on maternal exposure to multiple pollutants and the risk of isolated ventricular septal defects.

Numerous research works have established connections between maternal exposure to specific air pollutants and ventricular septal defects (VSDs), there are still gaps in understanding the complexities of combined exposures in real-world settings. This study seeks to investigate the correlation between simultaneous exposure to five air pollutants throughout pregnancy and the likelihood of isolated VSDs occurrence. It aims to address the gap between research focusing on individual pollutants and the complexities of real-world exposure scenarios. Utilizing data from China's National Population-Based Birth Defects Surveillance Network, we analyzed 850 isolated VSDs cases against 1,097,056 unaffected births. Using a random forest-based land use regression model, we estimated daily pollutant concentrations (SO2, NO2, CO, O3, PM2.5) at geocoded maternal residences from 2014 to 2017. Based on these daily estimates, trimester-specific exposure concentrations were derived using estimated date of conception and gestational weeks. Additionally, we devised an "air pollution score" to evaluate their cumulative exposure. The risk of isolated VSDs rose significantly with every 10-μg/m3 increase in air pollution score during pregnancy, especially the first trimester (OR 1.023, 95% CI 1.011-1.035), and the third trimester (OR 1.015, 95% CI 1.003-1.026). A linear relationship was observed between levels of air pollution scores during the entire pregnancy and the risk of isolated VSDs. The heightened risk linked to air pollution score during the first trimester surpassed that of the second and third trimesters. Besides, the results highlighted a pronounced risk among mothers in rural, low-income areas and being pregnant in cold season. By providing a more comprehensive assessment of the potential risks that pollutants pose to maternal and infant health, this study may offer important insights for public health policy and inform the development of new clinical tools for risk assessment and early screening.