Association of ambient PM_2.5 and its components with preeclampsia risk among pregnant women in a high-altitude region

The associations between ambient fine particulate matter (PM_2.5) and its components (sulfate, ammonium, nitrate, organic matter, and black carbon) and the risk of preeclampsia remain unclear, particularly in high-altitude regions where evidence is limited. This study aimed to provide novel insights into this issue. Lanzhou, China, was selected as a representative high-altitude city, and data from 169,484 women who delivered between 2016 and 2021 were included. Logistic regression models were used to evaluate the associations between individual exposure to PM_2.5 and its components and the risk of preeclampsia. The joint associations and the contribution weights of each component were further assessed using quantile g-computation. Additionally, distributed lag nonlinear models were applied to identify potential lagged associations. The results indicated that individual exposures to PM_2.5 and its components during the entire exposure period, the preconception period, and the first trimester were significantly associated with an increased risk of preeclampsia (p < 0.05). Mixed exposures to PM_2.5 components during the entire exposure period and the preconception period were also significantly associated with an increased risk of preeclampsia (p < 0.05), with black carbon (0.43) and ammonium (0.48) showing the highest positive weights, respectively. The strongest associations between high-level pollutant exposure and preeclampsia risk were observed during the preconception period or the first trimester. These findings suggest that public health interventions should target key PM_2.5 components and critical exposure windows to mitigate the risk of preeclampsia in high-altitude regions.