Neurology
Prenatal exposure to nitrogen dioxide and neurodevelopmental delays in children among Medicaid recipients: a national cohort study Wanyu Huang* Wanyu Huang Huang Huang Huang Huang Huang Huang Huang Huang Huang Huang Huang Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, US
Objective: Prenatal period is critical for brain formation and children’s neurodevelopment, yet few epidemiologic studies have examined the effects of prenatal exposure to gaseous pollutants, compared to PM2.5, particularly in underprivileged populations. Nitrogen dioxide (NO2) is one of the gaseous pollutants, also deemed as a traffic emission tracer.
Methods: We assigned ambient NO2 concentrations at the residential zip code of mother-infant pairs in a longitudinal cohort from the Medicaid Analytic eXtract (MAX). Identification of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) were based on ICD-9 codes. Weekly prenatal NO2 levels from spatiotemporal models were calculated over the gestational period. We applied distributed lag models (DLM) coupled with stratified Cox models (by county, birth year, race), adjusting for temperature, relative humidity, maternal age, behavioral risk factors (e.g. smoking, alcohol, drug use), SES (area-level), as well as season of delivery.
Results: We included 1,616,197 births from 2001 to 2014. We observed a positive association between a 10 ppb increase of prenatal NO2 exposure and the hazard of ASD across lag0 to 38 weeks during the gestational period, with a cumulative HR of 1.08 (95% CI: 1.01, 1.15) as the overall effect. We observed no association between NO2 exposure and ADHD (cumulative HR: 0.97, 95% CI: 0.94 – 1.00) (Fig. 1).
Conclusion: Among the Medicaid population, prenatal exposure to NO2 was associated with increased risk of ASD but not ADHD. This is the first and largest study providing evidence on gaseous pollutants and neurodevelopment delays, among the US socioeconomically disadvantaged population.
