Kim JY, et al. – Researchers examined environmental risk factors or biomarkers of autism spectrum disorder for their strength and validity via performing an umbrella review and appraising relevant meta-analyses of observational studies systematically. In all, they identified 46 eligible articles that included data on 67 environmental risk factors (544,212 cases, 81,708,787 individuals) and 52 biomarkers (15,614 cases, 15,433 controls). The analysis yielded convincing evidence suggesting the association of maternal factors, such as age and features of metabolic syndrome, with the risk of autism spectrum disorder. In addition, they noted the association of SSRI use during pregnancy with such risk upon comparing exposed and non-exposed groups; however, this association could be affected by other confounding factors, considering that pre-pregnancy maternal antidepressant use was also convincingly associated with a higher risk of autism spectrum disorder. As per findings from previous studies, underlying maternal psychiatric disorders comprise one of the possible confounding factors.