Windows of sensitivity for risk of adverse birth outcomes related to gestational PM_2.5 exposure: Evidence from a...

While numerous studies have associated maternal exposure to PM_2.5 with adverse birth outcomes, findings remain inconsistent and difficult to generalize. We aimed to investigate the causal relationship and window of sensitivity between gestational exposure to PM_2.5 and birth outcomes. We leveraged high-resolution satellite data to quantify gestational PM_2.5 exposure at the individual level, along with a combined model to determine daily relative risks (RRs) of birth outcomes in COVID-19 prelockdown and lockdown groups. RRs between the two groups were further compared using a longitudinal pre-post non-experimental design to identify sensitivity windows of adverse birth outcomes. A total of 73,781 pregnant women from the COVID-19 prelockdown group and 6267 pregnant women from the lockdown group were included for analysis. The daily mean PM_2.5 concentrations in the lockdown group decreased by 21.7% compared to the prelockdown group. During the first trimester, every 10 μg/m³ increase in PM_2.5 significantly increased the risk of congenital abnormalities of major organs such as the cardiovascular system, gastrointestinal tract, nervous system, urinary system, and respiratory system. Moreover, gestational exposure to PM_2.5 during the first trimester was associated with higher risks of premature delivery and term low birth weight. While PM_2.5 exposure during the second trimester was positively correlated with macrosomia. Gestational exposure to PM_2.5 is associated with increased risks of various adverse birth outcomes with specific sensitive windows. We demonstrated that gestational exposure to PM_2.5 increased risks of various adverse birth outcomes with specific window of sensitivity through the natural experiment design. Our findings underscore the urgent need for policies and initiatives targeting PM_2.5 reduction, especially during critical periods of pregnancy.