Despite prior small studies drawing the links between autism and anti-depressant use during pregnancy, a new study conducted by Danish researchers, which the team has called the largest to date, claims there is no definitive link between the two and that any supposed relationship in fact stems from the disorder, which the medication was intended to treat.

Mothers taking selective serotonin reuptake inhibitors (SSRIs) as part of their anti-depressant medication may do so for a variety of disorders. These range from depression to schizophrenia to certain types of eating disorders. Past research has failed to account for the variety of treated illnesses, the study authors argue, making the link between autism and anti-depressants difficult to take at face value.

"At this point, I do not think this potential association should feature prominently when evaluating the risks and benefits of SSRI use in pregnancy," lead researcher Dr. Anders Hviid, of the Statens Serum Institute in Copenhagen, told HealthDay. Dr. Hviid and his team combed through more than 600,000 children's records to collect their data. One limitation the researcher conceded, however, was the sample size for autistic children still remained small, at 52 subjects.

Researchers used the robust data to perform complex analyses of maternal health and the prescriptions mothers were taking while pregnant. While they found slight increases for autism when mothers were taking anti-depressants — seemingly in line with prior findings — these results vanished once the team controlled for the psychiatric disorders themselves. In other words, it wasn’t so much the medication that led to children developing autism; rather, the disorder for which they took that medication.

"How much of the risk is related to the medication, and how much is related to the underlying condition?" Christina Chambers, director of the Center for the Promotion of Maternal Health and Infant Development at the University of California, San Diego, told Health Day. "It's hard to tease out."

Mothers who stopped taking the SSRIs several months before giving birth were 46 percent more likely to deliver a child with autism, a finding the researchers say contributes to autism not being linked to the medication itself. Dr. Hviid told Reuters Health that such a finding should encourage doctors not to broach the topic of SSRIs during pregnancy in regards to the fetus’ risk for autism — especially considering the growing prevalence of the disorder, which now affects roughly one in 88 American children. In 2000, the rate was only one in 150.

Dr. Mark Zylka, a researcher from the University of North Carolina and expert in autism research, said the numbers behind psychiatric disorders and autism “are remarkably consistent,” and that future research into the link now has even greater “ammunition.”

 

Source: Hviid A, Melbye M, Pasternak B. Use of Selective Serotonin Reuptake Inhibitors during Pregnancy and Risk of Autism. NEJM. 2013.