Exposure to traffic-related air pollution and the risk of premature rupture of membranes: a cohort analysis of the Korean CHildren’s ENvironmental health Study (Ko-CHENS)

Premature rupture of membranes (PROM) is a common and consequential childbirth complication. Although several studies suggest that air pollution may elevate PROM risk, the evidence remains limited. We therefore examined the association between traffic-related air pollutants, other ambient pollutants, and PROM in a prospective mother–child cohort. We analyzed 4096 mother–child pairs enrolled in the Korean CHildren’s ENvironmental health Study (Ko-CHENS) core cohort. Ambient exposures to particulate matter (PM_2.5 and PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), and carbon monoxide (CO) were estimated using geostatistical kriging based on residential addresses recorded during pregnancy. PROM was identified from medical records completed by hospital clinicians at delivery. We fitted multivariable generalized linear mixed models with regional-level random effects, adjusting for potential confounders. PROM occurred in 4.0% of participants. PM_2.5 exposure throughout pregnancy was associated with increased PROM risk (odds ratio (OR) = 1.48, 95% confidence interval (CI) = 1.07–2.05) per interquartile-range increase (3.92 µg/m³). Compared with the lowest quartile, the 2nd, 3rd, and 4th quartiles of PM_2.5 were associated with ORs of 2.23 (95% CI = 1.30–3.84), 2.47 (95% CI = 1.42–4.33), and 2.48 (95% CI = 1.32–4.67), respectively. Elevated NO₂ exposure during the 2nd trimester (highest vs. lowest quartile) was also linked to higher PROM odds (OR = 2.31, 95% CI = 1.09–4.89). Residence in areas with very high traffic volume was associated with PROM (OR = 1.83, 95% CI = 1.06–3.16). Our findings indicate that traffic-related air pollutants, including PM_2.5 and NO₂, contribute to a higher risk of PROM. These results support the need for environmental policies targeting reductions in traffic-related emissions, particularly PM_2.5 and NO₂, to help prevent PROM and promote maternal health.