- The Washington Times - Tuesday, April 18, 2017

Two separate studies — one in Canada, one in the U.S. — have found that children whose mothers used antidepressants during pregnancy are not at an increased risk for autism or attention deficit hyperactivity disorder (ADHD).

The studies, which were published Tuesday in the Journal of the American Medical Association, contradict earlier studies that had found a link between antidepressant use during pregnancy and autism. The new studies’ researchers used “sophisticated statistical methods to adjust for possible measured and unmeasured confounding factors,” JAMA editors wrote in an editorial.

In Canada, researchers used high-dimensional propensity score (HDPS) analysis to “balance exposure group differences,” the study’s authors wrote.

Dr. Simone Vigod, the study’s lead author, said in an email to The Washington Times that without the statistical analysis, the results would appear to draw a link between antidepressants and autism.

“However, when HDPS methods were applied, this was no longer the case,” she told The Times.

Dr. Vigod and her research team tracked 35,906 births over five years. Of 2,837 pregnancies exposed to antidepressants like Zoloft, Celexa or Prozac, about 2 percent of children were diagnosed with autism spectrum disorder, the researchers found.

Using HDPS, the researchers found that any association was not significant enough to conclude that taking antidepressants during pregnancy caused autism or ADHD.

Dr. Vigod said their results are supported by a corresponding sibling analysis, in which researchers found that two children born to the same mother had similar risks for autism despite exposure to antidepressants in utero. A third analysis examined mothers who used antidepressants before but not during pregnancy and found a similar autism risk.

“Taken together, these results suggest that the increased risk for autism observed in previous studies was more likely to be due to the underlying maternal health condition or other factors, rather than the medication,” Dr. Vigod said.

In the other study, researchers in the U.S. and Sweden observed more than 1.5 million Swedish babies whose mothers self-reported antidepressant use during the first trimester. The children were born between 1996 and 2012, and researchers followed up with them through 2013.

Besides maternal antidepressant use, researchers examined a number of factors, including pregnancy, maternal and paternal traits, and stable familial characteristic shared by siblings, among others.

Researchers found that there was no increased risk for autism or ADHD but a small increased risk of premature birth.

“These results are consistent with the hypothesis that genetic factors, familial environmental factors, or both account for the population-wide associations between first-trimester antidepressant exposure and these outcomes,” the authors wrote.

For Dr. Vigod, the conclusions of the U.S.-Sweden study buoy her group’s findings.

“I believe that it was very promising that the study using Swedish data — conducted entirely independently from our study — came to a very similar conclusion,” Dr. Vigod said in an email. “Specifically, that in unadjusted and conventional analyses, it appeared as though there was a significant link between antidepressants and autism.

“Yet, in the sibling analysis (as in our study), the effect was no longer apparent. It is very difficult to have certainty on this question because the causes of autism are so multifaceted, but having such consistent findings arise from [two large population-based studies — both of which had very rigorous methods — increases our confidence in the findings.”

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