By Gene Emery
NEW YORK - Women who use selective serotonin reuptake inhibitors (SSRIs) during pregnancy are not more likely to have a child with autism, according to a new study from Denmark.
But children did have a higher than usual risk when their mothers took SSRIs before becoming pregnant, suggesting a possible link between a mother's preexisting mental health issues and autism.
"Our interpretation is that women with indications for SSRI use differ from women who do not use SSRIs because of these indications (depression, anxiety), and some of these differences are somehow related to an increased risk of having children who develop autism," said lead author Dr. Anders Hviid of the Statens Serum Institute in Copenhagen.
"Whether these differences are genetic, social or something completely different is speculation at this point," Hviid said.
The findings, combined with a separate analysis of the same database published online last month in Clinical Epidemiology, suggest people looking for a link between autism and SSRIs need to look elsewhere, said Dr. Mark Zylka of the University of North Carolina at Chapel Hill, who has studied autism but was not involved in the analyses.
"There's been a big question in the literature about whether these drugs affect brain development in any way and cause autism," he told Reuters Health.
A much smaller study conducted in Northern California and published in 2011 suggested SSRI use during pregnancy is tied to a two-fold higher risk of autism.
For the new study, released online today in the New England Journal of Medicine, the researchers used data on 626,875 babies born in Denmark in 1996 to 2005.
They recorded which mothers had taken an SSRI before or during pregnancy, based on a nationwide registry of prescription drugs.
Of the 3,892 children found to have an autism spectrum disorder, 52 had mothers who took one of those drugs while pregnant.
The researchers calculated that the risk of autism was 20% higher among children whose mothers took an SSRI during pregnancy. But the difference was very small, and it didn't reach statistical significance.
Children whose mothers once used SSRIs but stopped at least a few months before becoming pregnant were 46% more likely to have autism than other children. That finding was not likely to be a coincidence.
Because taking SSRIs during pregnancy didn't seem to cause autism, other factors may explain the higher rate among children whose mothers used the drugs before becoming pregnant, Hviid told Reuters Health in an email.
"At this point I do not think that this potential association (SSRI and autism) should feature prominently when evaluating the risks and benefits of SSRI use in pregnancy," he said.
"People who are taking these drugs prior to pregnancy often have some underlying psychiatric condition, and what they did find in the study was that having some psychiatric disorder does increase the risk of autism," Zylka said.
A study published last year showed children who had a parent or sibling with schizophrenia had an almost three times higher risk of developing autism (see Reuters Health story of July 5, 2012 here: http://reut.rs/1dmVFM8).
Similarly, in the new study, women who had been diagnosed with schizophrenia before delivery were three and a half times more likely to have a child with autism.
"The numbers are remarkably consistent," Zylka said.
The study also showed taking mood stabilizers or antipsychotics during pregnancy was linked to an increased risk of autism among children, he noted. That gives researchers "ammunition" for where to look in the future, Zylka said.
SOURCE: http://bit.ly/1bDXoxo New England Journal of Medicine, online December 18, 2013.
(c) Copyright Thomson Reuters 2013. Click For Restrictions - http://about.reuters.com/fulllegal.asp