July 25, 2017

Drexel study finds link between autism, antidepressant use in pregnant women

Contrary to recent studies suggesting otherwise, pregnant women who take antidepressants may be at a slightly higher risk of giving birth to a child who develops autism spectrum disorder, according to a team of researchers at Drexel University.

The latest study, published in The BMJ, examined a cohort of children born in Stockholm, Sweden, between 2001 and 2011. Drexel researchers, collaborating with the University of Bristol, found that children born to mothers who had taken antidepressants at any point in their pregnancy were 45 percent more likely to receive an ASD diagnosis.

Just 2 percent of those cases, however, could have been prevented had the women not taken antidepressant medication.

“Overall, the increase in risk was quite small,” Drexel researcher Brian Lee said. “Of children exposed to antidepressants during pregnancy, 4.1 percent had an autism diagnosis. In comparison, children of mothers with a history of a psychiatric disorder but who did not use antidepressants during pregnancy had a 2.9 percent prevalence of autism.”

Researchers chose to focus on prenatal antidepressant use because the medication has the potential to cross through the placenta and impact fetal development.

The findings come just a few months after another pair of studies published in the Journal of the American Medical Association found no association between prenatal antidepressant use and neurodevelopmental problems. 

While other studies have explored links between antidepressants and autism, the Drexel study was designed to root out confounding factors such as antidepressant use by the child's father during pregnancy. The study also compared the Stockholm children to their siblings — who present an elevated risk — and other children with similar characteristics.

Noting the discrepancy between various studies on this relationship — and the consequences it could have for pregnant women facing depression — the Drexel researchers are calling for additional studies that better account for confounding factors. 

“We conducted several analyses that seemed to support the validity of the findings,” Lee said. “For example, because a parental history of a psychiatric disorder is associated with increased risk of autism, we examined whether the father’s use of antidepressants was associated with autism. Because there was no increased risk with fathers’ use of antidepressants, this suggested that the increase with mothers’ use was not entirely due to the underlying psychiatric disorder.”

The link between prenatal antidepressant use and autism appeared only in children who did not also develop intellectual disabilities, a finding that supports the genetic basis of this form of the disorder.

Despite the small correlation found in the study, researchers advise women and clinicians not to base their decisions about antidepressant use on the results of any one study. Suspending use of the medication could pose serious risks during pregnancy, both to the mother and the fetus, and the mental health benefits of such drugs should be taken into consideration.

“Balancing benefits and risks of taking medications during pregnancy is a complex and often difficult decision,” said lead author Dheeraj Rai of Bristol University. “Our advice would be for women to discuss their concerns with their treating clinicians who will be able to help them weigh the pros and the cons.”