Effect of individual and combined ambient air pollutants exposure on the risk of preeclampsia: a retrospective cohort study in Tangshan, China

Evidence regarding air pollution and preeclampsia (PE) remains inconsistent. This study aimed to evaluate the association of individual and combined exposure to PM10, PM2.5, SO2, NO2, CO, and O3 from 12 weeks preconception to 26 weeks of gestation with PE risk in Tangshan, China. This retrospective cohort study analyzed 18,045 deliveries at Tangshan Maternal and Children Health Hospital between September 15, 2020 and September 30, 2022. Single-pollutant effects were assessed using logistic regression, restricted cubic spline (RCS), and distributed lag non-linear model (DLNM). Quantile g-computation (Qgcomp) was employed to quantify the joint effect of multi-pollutant mixture. Subgroup analysis was performed by conception method. Among 1,180 PE cases (6.54%), adjusted analyses revealed that each 10 µg/m3 increase in PM10 (OR = 1.13, 95%CI:1.06–1.21) and PM2.5 (OR = 1.30, 95%CI:1.12–1.52) was positively associated with PE risk, while a 0.1 mg/m3 increase in CO showed a modest inverse association (OR = 0.98, 95%CI:0.96-1.00). Linear exposure-response (E-R) relationships were observed for PM10, PM2.5, and CO (P for overall 0.05), whereas SO2 and NO2 exhibited nonlinear patterns (P for overall < 0.001, P for nonlinearity < 0.001). Susceptible windows were identified for PM10 (preconception weeks 2–4), PM2.5 (preconception weeks 6–12 and gestational weeks 10–19), SO2 (gestational weeks 18–20), NO2 (gestational weeks 17–26), and O3 (preconception weeks 1–5). Each quartile increase in multi-pollutant exposure was associated with a 26% higher risk of PE (OR = 1.26, 95%CI:1.06–1.49), with positive weights for SO2 (42.90%), NO2 (25.67%), PM2.5 (21.84%), and PM10 (9.59%). The assisted reproductive technology (ART) subgroup showed stronger associations for PM2.5 (gestational weeks 20–26) and O3 (gestational weeks 8–16). Single particulate matter (PM) exposure, particularly PM2.5, from preconception through mid-pregnancy is associated with increased PE risk. Pollutant-specific susceptible windows exist, with PM10, PM2.5, and O3 most influential during preconception, and SO2 and NO2 most impactful during the second trimester. Mixed pollutant exposure is also associated with higher PE risk, driven primarily by SO2. Moreover, ART pregnancies appear more vulnerable to PM2.5 in the second trimester and to O3 between late first and early second trimesters at the weekly exposure level. These findings warrant further investigation into mechanisms and targeted prevention.