Two studies have cast doubt on research that claimed the likelihood of autism is increased among children of mums who take antidepressants during pregnancy.
Published in the Journal of the American Medical Association, the latest findings show no raised risk of autism in offspring of mothers who take antidepressants in the first trimester, after adjusting for confounding factors and comparing siblings.
One study looks at 1.5 million births in Sweden, and the other analyses Canadian data on almost 36,000 babies - including medication use and siblings.
In the Canadian study, of the 2837 pregnancies (7.9%) exposed to antidepressants, 2% of children were diagnosed with autism spectrum disorder.
This is a higher rate for autism spectrum disorder compared with unexposed children, but after adjusting for confounding factors, the difference is no longer statistically significant, the authors say.
The association is also not significant when exposed children are compared with unexposed siblings.
“Although a causal relationship cannot be ruled out, the previously observed association may be explained by other factors,” the researchers write.
Of the 1.5 million babies born in Sweden between 1996 and 2012, more than 22,000 (1.4%) of the 950,000 mothers reported using antidepressants, mostly SSRIs, in the first trimester.
According to earlier research, these children had roughly twice the risk of having autism, but after controlling for multiple other risk factors, the researchers did not find any increased risk of autism, ADHD or reduced fetal growth.
"To our knowledge, this is one of the strongest studies to show that exposure to antidepressants during early pregnancy is not associated with autism, ADHD or poor fetal growth when taking into account the factors that lead to medication use in the first place," said lead author Professor Brian D’Onofrio of Indiana University.
"The additional comparisons provide further evidence that other factors — not first-trimester exposure to antidepressants — explain why women who took these medications during early pregnancy were more likely to have offspring with these pregnancy and neurodevelopmental problems.
"Balancing the risks and benefits of using antidepressants during pregnancy is an extremely difficult decision that every woman should make in consultation with her doctor," Professor D’Onofrio added.
"However, this study suggests use of these medications while pregnant may be safer than previously thought."