The FDA has just issued a warning to doctors and patients that several varieties of migraine medication should not be prescribed to pregnant women. New results from an ongoing study have found that the drugs,when taken by women who are pregnant, can negatively affect children's IQs.

There are still some unknowns about how the connection works, but the FDA feels that it’s better to be safe and avoid the medications if at all possible, barring certain "last resort" circumstances.

A study last month linked taking valproate medications during pregnancy to a higher risk of autism in the child.

The medications in question are valproate products, which include valproate sodium (Depacon), divalproex sodium (Depakote, Depakote CP and Depakote ER), valproic acid (Depakene and Stavzor), as well as their generic versions.

While these drugs may be used to treat migraines, the medications are not primarily migraine medications. They are technically drugs that are used to treat epileptic seizures as well as the manic phases of bipolar disorder. The drugs already carry a black box warning for pregnant women because they have been associated with birth defects in the past. Now, the FDA will add to the warning the risk of interfering with a child's mental development, lowering his or her IQ.

The new study found a concerning link between valproate products used during pregnancy and a child’s IQ at age six. Children of mothers taking the drugs had IQs that were between eight and 11 points lower, depending on the specific medication, than children whose mothers took other types of antiepileptic medications. An earlier study in 2011 found that the medications were also linked to reduced IQ in children at age three.

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

The FDA will be working with manufacturers to change the warning from category D, in which the drug’s benefits outweigh the risks for a particular use, to category X, in which the risks outweigh the benefits.

A study last month linked valproate medications during pregnancy to a higher risk of autism in the child. When taken during pregnancy, certain migraine medications may affect a baby's mental abilities.

It is not clear at what point during pregnancy the risks are highest, so to be safe the FDA has recommended against using these drugs during pregnancy if at all possible. They advise all women taking the medications to use effective birth control and, if pregnancy does occur, to contact their doctors immediately.

Some women with bipolar disorder who are doing well on valproate medications may be advised to continue them.

Talk to your doctor if you have any concerns about the medications you’re taking, particularly if you are pregnant or plan to be.

Visit the FDA’s website for the full safety advisory.