Taking selective serotonin reuptake inhibitors (SSRIs) during pregnancy, in and of itself, does not increase the risk that a child will develop autism, according to a large new study. The report – which largely exonerates this antidepressant – appears today in the New England Journal of Medicine.
In 2011, U.S. researchers associated SSRI use during pregnancy with a two-fold to three-fold increase in autism risk. That study looked at the medical records of 1,805 California women and their children, including 298 children with autism spectrum disorder (ASD).
Teasing apart possible risk factors
The new study analyzes the national health records of nearly 627,000 Danish births. This included 52 children who developed ASD. In unadjusted numbers, the Danish study likewise found an increased prevalence of autism among children born to women prescribed SSRIs during pregnancy. However, this increased risk all but disappeared when the researchers adjusted for the presence of underlying depression in the mother.
In other words, when they looked just at women who had been diagnosed with depression, they found no difference in autism rates between those who were prescribed SSRIs during pregnancy and those who weren’t.
To further test this finding, the Danish researchers looked at autism rates among the children of women whose SSRI prescriptions were stopped at least 6 months before their pregnancies. Presumably most of these women had a propensity for depression, while none of their children were knowingly exposed to SSRIs during prenatal development. And in fact, autism rates were elevated among these children.
The findings suggest that a mother’s underlying mental-health condition – rather than SSRI use – is the factor behind higher autism risk seen in previous studies, the researchers conclude. This is in line with recent research showing that many of the genes that predispose to depression, bipolar disorder, attention deficit and hyperactivity disorder and schizophrenia also predispose to autism.
Importance of managing depression during pregnancy
“These new results about SSRIs are reassuring,” comments developmental pediatrician Paul Wang, Autism Speaks senior vice president for medical research. “The decision to use any medication during pregnancy should be discussed by the mother and her physician. But depression can pose serious risks if it’s untreated. So it’s important to have safe treatment options.”
While the Danish study’s size increases the reliability of its findings, the results may not apply to other populations, cautions epidemiologist Michael Rosanoff, Autism Speaks associate director for public health research. The reported prevalence of ASD in Denmark, for example, is 1 in 160. That’s a contrast to 1 in 88 in the U.S. Such stark differences may suggest that other factors need to be taken into consideration.
The Danish researchers point out another weakness of their study: They based estimates of SSRI use on prescription records. Many women who had prescriptions may have stopped taking the medication when they became pregnant. This would have falsely lowered the study’s estimate of autism risk. The investigators concluded their report with a call for further research to clarify such uncertainties.
For further perspective, also see “Autism, Antidepressants and Pregnancy” and “Can Taking Medication during Pregnancy Cause Autism?” in the Autism Speaks “Got Questions?” blog.