Women who use antidepressants in the later stages of pregnancy – particularly selective serotonin reuptake inhibitor (SSRI) drugs – have an increased risk of giving birth to children with autism spectrum disorder, according to a new study by Montreal researchers.
The study published in JAMA Pediatrics on Monday found an 87-per-cent higher risk of autism among babies born to women who used antidepressants during the second or third trimesters of pregnancy. One of the authors of the study, Anick Bérard, a professor of the faculty of pharmacy at the University of Montreal and a researcher at the CHU Sainte-Justine Research Centre, explained that autism affects about 1 per cent of the general population.
“If you take antidepressants in late pregnancy, you increase that risk to 1.87 per cent,” Dr. Berard said, noting that when she and her colleagues looked specifically at the use of SSRIs, the most commonly used class of antidepressants, “that class was associated with more than a doubling of the risk of having a child with autism. So again, going from 1 per cent to above 2 per cent.”
The researchers based the findings on data collected on 145,456 babies born in Quebec between January, 1998, and December, 2009.
Scientists have yet to untangle the multitude of factors that contribute to autism, which are believed to include genetic and environmental risks.
In their study, Dr. Bérard and her colleagues acknowledge that the association between using antidepressants during pregnancy and autism spectrum disorder in children is “still controversial.” But she warned that women suffering from depression and their doctors should consider alternative treatments, including exercise and psychotherapy.
While depression is common during pregnancy, affecting up to 15 per cent of women, Dr. Bérard noted that the vast majority – 80 to 85 per cent – of these women are mildly to moderately depressed and thus may be effectively treated without antidepressants.
“What we’re saying is we have to think of other treatment options, at least during pregnancy,” she said – “... especially with the overwhelming amount of evidence pointing to increased risk” of using antidepressants.
She said a possible explanation for the heightened risk of autism associated with SSRIs is that the drugs may cross the placenta and block the neurotransmitter seratonin, which affects the division and development of healthy brain cells.
Evdokia Anagnostou, a senior clinician scientist at Toronto’s Bloorview Research Institute who was not involved in the study, said it’s important to keep in mind that the absolute number of cases of babies who develop autism is still very small. Even with the heightened risk identified in the JAMA Pediatrics study, the vast majority of pregnant women who took antidepressants did not haves babies with autism spectrum disorder.
“It’s a rare event,” said Dr. Anagnostou, whose work focuses on autism and other neurodevelopmental disorders.
She added that with this JAMA Pediatrics study and other previous studies linking autism to antidepressant use, it’s uncertain whether the elevated risk of autism is a result of the antidepressants themselves or the severity of the women’s depression. It’s possible, for instance, that only women with severe depression are prescribed SSRIs, while those with mild or moderate forms of depression are not, she suggested.
“It’s clear there’s a small association, but it’s not clear whether the SSRIs are involved in the causation or whether the severe depression is involved,” she said.
If severe depression itself increases the risk of autism, women who opt not to take SSRIs may actually find themselves at higher risk, Dr. Anagnostou said.
Studies such as this point to important questions about the effects of seratonin manipulation in developing fetuses, she said. But she noted: “I’m not sure that they have given us enough information yet to have large public health implications.”Report Typo/Error