To the Editor With great interest we read an article by Pagalan et al1 that reported an association between maternal exposure to nitric oxide (NO) during pregnancy and the development of autism spectrum disorder (ASD) in offspring. We came across several issues in this article that warrant caution in the interpretation of the data.
The authors used the residential postal codes of mothers to estimate the monthly mean air pollution exposure, and it is possible that most children were exposed to the same environmental conditions as their mother. In addition to pregnancy, the first postnatal year is a crucial period of neurodevelopment, and environmental perturbations may have a deleterious effect on brain development.2 The association perceived as prenatal might essentially be associated with the direct exposure of the offspring to similar environmental conditions during the postnatal phase of neurodevelopment. Although this study was unable to differentiate the risk across the trimesters, previous studies3 have found higher risk associated with exposure to particulate matter that have diameter less than 2.5 μm during the third trimester, which is temporally proximal to postnatal period.
Chandrakumar A, ‘t Jong GW. Maternal Exposure to Air Pollution During Pregnancy and Autism Spectrum Disorder in Offspring. JAMA Pediatr. 2019;173(7):697–698. doi:10.1001/jamapediatrics.2019.0925
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