Tak Kyu Oh, In‐Ae Song
Background Prenatal exposure to ambient air pollution has been implicated in adverse neurodevelopment, but evidence from large‐scale, long‐term studies in Asian populations remains limited. We examined the association between in utero exposure to multiple air pollutants and the risk of neurodevelopmental disorders (NDD) in offspring using a nationwide cohort in South Korea. Methods We conducted a nationwide retrospective cohort study using linked administrative health and environmental data. A total of 1,436,685 children born between January 1, 2010, and December 31, 2014, were identified from the National Health Insurance Service database and followed up through December 31, 2023. Maternal exposure to nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), ozone (O 3 ), and particulate matter ≤10 μm (PM 10 ) was estimated by linking residential postal codes to fixed‐site monitoring data. NDD diagnoses were identified from healthcare claims. Adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) were estimated using multivariable Cox proportional hazards models adjusting for maternal sociodemographic, medical, obstetric, and neonatal covariates. Results During up to 13 years of follow‐up, 140,971 children (9.8%) were diagnosed with an NDD. Prenatal exposure to NO 2 showed the strongest association: each 0.01‐ppm increase was associated with an 18% higher hazard of NDD (aHR 1.18, 95% CI 1.17–1.19; p < .001). SO 2 exposure also demonstrated a small but statistically significant association (per 0.001‐ppm increase: aHR 1.01, 95% CI 1.01–1.02; p = .008). These associations persisted across major NDD subtypes – including intellectual disabilities, developmental delays, and behavioral or emotional disorders – and remained robust in trimester‐specific, stratified, and sensitivity analyses. Conclusions Prenatal exposure to ambient air pollutants – particularly NO 2 and SO 2 – is associated with increased long‐term risk of NDD in offspring. These findings highlight the neurodevelopmental vulnerability of the prenatal period and underscore the need for strengthened environmental policies to reduce maternal exposure to harmful pollutants.