In utero exposure to the medications that treat depression may increase the risk of autism spectrum disorders in less than 1 percent of cases. St. Louis Cardinals pitcher Shelby Miller talks with friends during a fund raiser for the Thompson Center for Autism and Neurodevelopmental Disorders in St. Louis on May 16, 2013. UPI/Bill Greenblatt | License Photo

STOCKHOLM, Sweden, May 17 (UPI) -- In utero exposure to depression medications may increase the risk of autism spectrum disorders in less than 1 percent of cases, researchers in Sweden say.

First author Dheeraj Rai, a clinical lecturer at the Department of Public Health Sciences at Karolinska Institutet in Stockholm, and colleagues at the University of Bristol; Avon and Wiltshire Partnership Mental Health NHS Trust in Bristol, England; and Drexel University School of Public Health on Philadelphia said the study involved 4,429 cases of autism spectrum disorder -- 1,828 with and 2,601 without intellectual disability and 43,277 age and sex matched controls.


The study involved 1,679 cases of autism spectrum disorder and 16,845 controls with data on maternal anti-depressant use.

The study, published in the British Medical Journal, said parental depression and other characteristics were recorded in administrative registers before the birth of the child. Maternal anti-depressant use, recorded at the first antenatal interview, was available for children born from 1995 onwards.

A history of maternal -- but not paternal -- depression was associated with an increased risk of autism spectrum disorders in offspring, the study said. In the subsample with available data on drugs, this association was confined to women reporting anti-depressant use during pregnancy irrespective of whether selective serotonin reuptake inhibitors or non-selective monoamine reuptake inhibitors were reported, the study said.

"Whether this association is causal or reflects the risk of autism with severe depression during pregnancy requires further research," the study authors wrote in the study. "However, assuming causality, anti-depressant use during pregnancy is unlikely to have contributed significantly towards the dramatic increase in observed prevalence of autism spectrum disorders as it explained less than 1 percent of cases."