In utero exposure to antidepressants may influence autism risk

A new study from researchers at Drexel University adds evidence that using common antidepressant medications during pregnancy may contribute to a higher risk of autism spectrum disorders (ASD) in children, although this risk is still very small.

Results from past studies of prenatal use of selective serotonin reuptake inhibitors (SSRIs) and ASD risk have not been consistent. An ongoing challenge in this line of research is trying to tease apart potential effects of the medication on risk from the effects associated with the condition for which the medication was prescribed (most commonly depression). Based on past studies, both SSRIs and genetic factors associated with depression are likely associated with greater risk of ASD.

This new study, published online ahead of print last month in the Journal of Autism and Developmental Disorders, suggests that under-reporting of maternal depression, if not properly considered in analyses, may influence results of studies trying to address this question.

In the study, the Drexel team analyzed large population based registers of nearly 750,000 births in Denmark from 1997 through 2006. They found that about 1.5 percent of children born to women who had taken an SSRI during pregnancy were diagnosed with ASD, compared to about 0.7 percent of children born to an otherwise similar group of women not taking the medication.

"We found a two-fold increased risk for ASD associated with in utero exposure to SSRIs compared to the unexposed reference group" said lead author Nicole Gidaya, PhD. "More importantly, in our analysis we accounted for under-reporting of maternal depression in the register. This suggests that under-reporting of the confounder, maternal depression, may be a limitation in approaches previously used in the other studies."

Gidaya, who performed this study while a doctoral student in the Drexel University School of Public Health, noted that "if the increased ASD risk we saw here is real, it is important to realize that the number of ASD cases that could be prevented by reducing SSRI exposure in pregnancy still represents only a small fraction of overall cases of ASD."

Antidepressant Use in Pregnancy Tied to Autism Risk Boys with autism were three times more likely to have been exposed to antidepressants known as SSRIs in the womb than typically developing children, according to new research.

The new study also found that boys whose mothers took SSRIs -- drugs including Celexa, Lexapro, Paxil, Prozac and Zoloft -- during pregnancy were also more likely to have developmental delays.

Results of the study were published online April 14 and in the May print issue of Pediatrics.

"We found prenatal SSRI exposure was almost three times as likely in boys with autism spectrum disorders relative to typical development, with the greatest risk when exposure is during the first trimester," said study co-author Li-Ching Lee, an associate scientist in the department of epidemiology at Johns Hopkins Bloomberg School of Public Health, in Baltimore.