Valproate in pregnancy tied to autism risk
Epidemiology
Last Updated: 2013-04-23 19:35:29 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Women who take the epilepsy drug valproate during pregnancy are three times more likely to have a child with an autism spectrum disorder, suggests a nationwide study from Denmark.
Previous studies have found more birth defects and lower intelligence among children of mothers who took valproate, but the new work represents the "strongest evidence to date" of a link between the drug and autism, according to an editorial published with the study on Tuesday.
The results don't prove the drug, also sold as valproic acid, causes autism. But researchers were able to account for a number of underlying factors - such as the age and health of the mothers and the babies' fathers - that make the study more convincing, Dr. Christopher Stodgell said.
"This finding isn't necessarily a brand new finding, but it's an important finding in that (researchers studied) really a much larger population, and they also looked at some other underlying drivers," said Dr. Stodgell, who studies the origins of autism at the University of Rochester Medical Center but wasn't involved in the new research.
For the new study, researchers tracked 656,000 kids born in Denmark between 1996 and 2006. Using a large prescription drug database, they found that just under 6,600 mothers of those children had epilepsy, and 508 women took valproate while pregnant.
By 2010, 4.4% of the kids whose mothers had taken valproate during pregnancy were diagnosed with any ASD, including 2.5% with autism.
In contrast, 1.5% of all babies in the study had an ASD and 0.5% had autism, the study team reported in the Journal of the American Medical Association.
Mothers' underlying epilepsy didn't fully explain the link, according to Dr. Jakob Christensen from Aarhus University and his colleagues. They found that autism rates were higher when mothers had used valproate during pregnancy than when they had previously used it but stopped before conceiving.
"Valproate is an effective drug, but it appears that it is being prescribed for women of childbearing potential at a rate that does not fully consider the ratio of benefits to risks," wrote Dr. Kimford Meador and Dr. David Loring from Emory University in Atlanta, in an editorial.
Valproate could affect maturation of a fetus's brain, Dr. Christensen suggested, including the neurotransmitters.
But for women with certain syndromes or generalized epilepsy, there aren't necessarily other good options. Stopping valproate in that case isn't a good idea, Dr. Christensen said.
"Even those that are exposed to this drug, there's still a good chance - more than a 95% chance - that their child will never develop signs of autism," he added.
The study didn't take into account whether women drank during pregnancy, or if they took folic acid.
Dr. Christensen also said there are steps to reduce the risks for pregnant women who must stay on valproate, such as using the lowest possible dose and dividing it up during the day.
SOURCE: https://bit.ly/11LEoFn
JAMA 2013.
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