New research published Wednesday in the journal Neurology reveals both good and bad news for expectant mothers who take medication to deal with their epilepsy.

The researchers tested the IQ and cognition of UK children born to 171 women who had taken one of three antiepileptic drugs during their pregnancy — levetiracetam, topiramate, and valproate — and compared them to one another as well as to children whose mothers hadn’t taken any medication. The children, aged 5 to 9, whose mothers had taken levetiracetam, topiramate, or no drug had similar scores in IQ, verbal and nonverbal comprehension, and visual processing speed.. Those whose mothers had taken valproate, however, had an average IQ score 11 points lower than everyone else.

"Over the past few years, doctors have been moving away from prescribing valproate to pregnant women, shifting them to the two newer antiepileptic drugs. But, until now, there hasn't been any definitive research to understand what implications for IQ and development these two drugs may have.” said lead author Dr. Rebecca Bromley, a biologist at England’s University of Manchester, in a statement. “From the results, we have concluded that — at the moment — levetiracetam and topiramate have no discernable impact on childhood intellectual development.”

The current study is only the latest by Bromley and her colleagues to suggest that valproate may do more harm than good for mothers-to-be. A 2014 study of children from the ages of 3 to 5, also published in Neurology, found marked differences in language and motor development skills between the group of mothers who had taken valproate and those who had taken levetiracetam or nothing at all. In 2015, another study that looked at the 6-year old children of valproate-taking mothers found an average 9-point IQ decrease associated with its use.

Valproate, a drug in existence since the late 1800’s, has also been used to treat migraines and mental conditions like bipolar disorder, but its hazardous effects on developing fetuses have been documented for some time. In addition to learning disabilities, use of valproate during pregnancy has been linked to an increased chance of facial and skeletal birth defects like spina bifida. As recently as the early 1990’s, however, there was little doctors could do to mitigate these risks other than to lower the drug’s dosage. With the release of topiramate and levetiracetam onto the market (1996 for the former, 2000 for the latter), there was hope these drugs would be less riskier for expectant women and their children, one now further validated by the current study.

Bromley does advocate caution for the time being, though.

"However promising a start our findings are, we do acknowledge larger studies need to be carried out regularly to ensure these drugs do not change the thinking abilities of children in the future," she said.

For those epileptic mothers who worry about balancing out their own health with that of their future children, however, Bromley hopes that her team’s findings can be worthwhile.

"Expectant mothers with epilepsy may need to continue their drug regime during pregnancy; this research may give them some reassurance that — provided they are prescribed topirimate and levetiracetam — they will a statistically good chance of normal, healthy development in their children," she said.

Source: Bromley R, et al. Neurology. 2016.