Pregnant women should not use certain preventive migraine medications because the drugs have been linked to lower IQ scores in children who were exposed to these drugs in the womb, according to the U.S. Food and Drug Administration (FDA).

Pregnant women should avoid taking valproate sodium and related medications. Valproate products include valproate sodium (Depacon), divalproex sodium (Depakote, Depakote CP and Depakote ER), valproic acid (Depakene and Stavzor) and their generics.

These medicines, which are used in the treatment of migraine, seizures and manic disorders, were already known to cause fetal problems, including birth defects, but a recent study found further evidence of the IQ risk, which led to the latest warning.

“Valproate medications should never be used in pregnant women for the prevention of migraine headaches because we have even more data now which show that the risks to the children outweigh any treatment benefits for this use,” said Russell Katz, MD, director of the Division of Neurology Products in the FDA’s Center for Drug Evaluation and Research.

The recent Neurodevelopmental Effects of Antiepileptic Drugs (NEAD) study found that in uteroexposure to valproate products caused IQ scores to be eight to 11 points lower in 6-year-old children when compared to children who had been exposed to other anti-epileptic drugs.

Additionally, another recent valproate-related study showed mothers who used the medication during pregnancy had a five times higher risk of having a child with an autism spectrum disorder compared to children whose mothers did not take the drug.

The FDA warns that women who are pregnant or who become pregnant while taking one of these medications should talk to their health care professional immediately. The FDA also cautioned women not to stop taking their medication without talking to their health care professional because stopping treatment suddenly can cause serious and life-threatening medical problems for the woman or the developing fetus.

According to the FDA, the agency is working with manufacturers to make changes to the drug labels to change the pregnancy category for prevention of migraine headache to category X (the drug’s risks outweigh the drug’s benefits for this use) from category D (the drug’s benefits outweigh the drug’s risks for this use). Valproate products will remain category D for the other two approved indications, epilepsy and manic episodes associated with bipolar disorder.