Umeå universitets logga

Background: – Prenatal exposure to ambient air pollution has been linked to autism spectrum disorder (ASD), but evidence from low-exposure settings such as Denmark remains limited.

Objective: – We aimed to examine the association between prenatal exposure to particulate matter with a diameter of ≤2.5 µm (PM2.5), black carbon (BC), and nitrogen dioxide (NO2) and ASD in children, and to identify the most susceptible groups.

Methods: – We included 850, 361 children born in Denmark between 1990 and 2004 and followed them for ASD diagnoses in the Danish Patient Register until age 15 years. We assigned prenatal PM2.5, BC, and NO2 levels (Danish Eulerian Hemispheric Model/Urban Background Model) at the mother’s residential address at delivery, and examined the association with ASD using logistic regression with a random intercept for municipality, including interaction terms to assess effect modification by sex, maternal age, smoking status, and socioeconomic status (SES).

Results: – An interquartile range increase in prenatal exposure to PM2.5, BC, and NO2 was associated with ASD (adjusted odds ratio; 95% confidence interval = 1.04; 1.00–1.07 per 2.8 µg/m3, 1.05; 1.03–1.08 per 0.3 µg/m3, and 1.15; 1.11–1.19 per 8 µg/m3, respectively). The association between BC and ASD persisted even after adjusting for PM2.5. Additionally, the associations between prenatal air pollution exposure and ASD were stronger among children born to older mothers.

Conclusion: – We found that prenatal exposure to air pollution was associated with ASD even at the relatively low exposure levels observed in Denmark, underscoring the importance of air pollution reduction for ASD prevention. The association with BC was independent of that with PM2.5, and children born to older mothers appeared to be particularly vulnerable.