By Dennis Thompson
TUESDAY, April 18, 2017 (HealthDay News) -- Taking antidepressants during pregnancy doesn't appear to raise a child's risk of autism, once other factors that could influence the risk are taken into account, two new studies suggest.
"For a woman who needs to take this medication for her mental health and for her psychiatric stability, these results certainly suggest she shouldn't go without treatment," said Dr. Simone Vigod, senior author of one study and a psychiatrist at Women's College Hospital in Toronto.
Depression during pregnancy can be dangerous for both mother and child. Pregnant women with untreated depression are more likely to have severe postpartum depression, and their children are more likely to be born prematurely or at a low birth weight, Vigod said.
But earlier studies found a significant association between first-trimester exposure to antidepressants and autism spectrum disorder in children, sparking some concern about prescribing the drugs to pregnant women, researchers explained in background notes.
Two separate research teams suspected that those earlier findings might have been flawed if all the different factors that contribute to autism hadn't been weeded out, so they set to work on more detailed analyses. One team focused on a set of Canadian children, while the other evaluated a group of Swedish children.
Vigod and her team reviewed almost 36,000 Canadian children, just over 2,800 of whom were exposed to antidepressants in the womb. About 2 percent of the kids exposed to antidepressants were diagnosed with autism.
The analysis included matching moms who took antidepressants against those who didn't based on a series of 500 different variables in their life and health, Vigod said.
The researchers also compared siblings born with antidepressant exposure against brothers or sisters with no exposure in the womb. They also compared the babies of moms who stopped antidepressant use before pregnancy against those whose mothers continued using and those who never took the medications.
Another team performed a similar evaluation of more than 1.5 million children born in Sweden. These researchers performed the sibling comparison and the comparison between mothers conducted in the other study. But they also did an analysis considering whether the children's fathers had taken antidepressants during pregnancy.
"If that was associated with the problems in the offspring, it couldn't be due to the exposure during pregnancy, but rather due to factors that lead either parent to have depression and use the medication," explained senior study author Brian D'Onofrio. He's a professor of developmental psychopathology at Indiana University Bloomington.
Both teams came to the same conclusion -- the increased risk of autism disappeared when all other factors were taken into account. D'Onofrio's team also found that a pregnant woman's antidepressant use was not related to an increased risk of attention deficit hyperactivity disorder (ADHD) in her children.
Concern about antidepressant use has stemmed from the fact that the medications can cross the placenta and get into the brain of a fetus, potentially affecting future development, Vigod said.
However, genetics also likely play a huge part in autism risk, and must be considered, she said.
"It's known that autism and depression and anxiety and other psychiatric illnesses share some genetic components," Vigod said. "It could be that a child born to a mom who took an antidepressant might have a higher risk simply because there's a genetic predisposition that has nothing to do with the drug."
Women fighting depression also might be more likely to engage in behaviors that could affect their pregnancy, Vigod added. They might smoke, drink, eat unhealthy foods, or not get enough sleep.
Both Vigod and D'Onofrio said their findings do not close the book on this debate. Follow-up studies are needed to confirm their results.
Thomas Frazier, chief science officer of Autism Speaks, agreed. "It's really too early to say anything to prospective mothers based on this study," Frazier said. "I wouldn't want to get too excited in either direction."
One thing these results do highlight is the need to screen pregnant women for depression, D'Onofrio said.
Pregnant women diagnosed with depression may be able to receive psychotherapy instead of medication, but that's a discussion that needs to take place between a woman and her doctor, he said.
"Our study suggests the risk of antidepressant use is lower than we previously feared, but each case must be considered on its own merits," D'Onofrio said.
Dr. Andrew Adesman is chief of developmental and behavioral pediatrics for Cohen Children's Medical Center in New Hyde Park, N.Y. He said the two studies "should provide further reassurance for women to continue taking their antidepressants when pregnant, if that is what their doctor has recommended."
The studies "are also an important reminder to both the public and to medical professionals how important it is to control for as many relevant clinical factors as possible," Adesman added.
Both studies were published April 18 in the Journal of the American Medical Association.