Background: Prenatal exposure to air pollutants has been suggested as a possible etiologic factor
for the occurrence of autism spectrum disorder.
Objectives: We aimed to assess whether prenatal air pollution exposure is associated with
childhood autistic traits in the general population.
Methods: Ours was a collaborative study of four European population-based birth/child cohorts—
CATSS (Sweden), Generation R (the Netherlands), GASPII (Italy), and INMA (Spain). Nitrogen
oxides (NO2, NOx) and particulate matter (PM) with diameters of ≤ 2.5 μm (PM2.5), ≤ 10 μm
(PM10), and between 2.5 and 10 μm (PMcoarse), and PM2.5 absorbance were estimated for birth
addresses by land-use regression models based on monitoring campaigns performed between 2008
and 2011. Levels were extrapolated back in time to exact pregnancy periods. We quantitatively
assessed autistic traits when the child was between 4 and 10 years of age. Children were classified
with autistic traits within the borderline/clinical range and within the clinical range using
validated cut-offs. Adjusted cohort-specific effect estimates were combined using random-effects
meta-analysis.
Results: A total of 8,079 children were included. Prenatal air pollution exposure was not associated
with autistic traits within the borderline/clinical range (odds ratio = 0.94; 95% CI: 0.81, 1.10
per each 10‑μg/m3 increase in NO2 pregnancy levels). Similar results were observed in the different
cohorts, for the other pollutants, and in assessments of children with autistic traits within the
clinical range or children with autistic traits as a quantitative score.
Conclusions: Prenatal exposure to NO2 and PM was not associated with autistic traits in children
from 4 to 10 years of age in four European population-based birth/child cohort studies.NonePublishe
