Now, new British research suggests that the drug levetiracetam does not pose a major risk to the neurological development of the fetus, although there's more evidence that another drug -- valproate -- may cause some problems.
"These results are heartening, as the use of levetiracetam has increased in recent years, but there has been limited information on its effect on the thinking, movement and language abilities of children," study author Rebekah Shallcross of the University of Liverpool said in a news release from the American Academy of Neurology.
"This is the first study to look at the effects of levetiracetam, and further research is needed before we can be certain there are no associations," Shallcross cautioned.
The study of 3- and 4-year-olds tracked 53 children whose mothers took levetiracetam (brand name Keppra), 44 whose mothers took valproate (known by several brand names), and 151 children of mothers who didn't take any drugs during pregnancy.
The researchers examined the children's abilities in areas such as thinking, movement and language.
The children whose mothers took levetiracetam weren't different overall from those whose mothers took no drugs. However, those who took valproate scored lower on tests of movement, expressive language and language comprehension than those who took levetiracetam.
Two experts unconnected to the study said it provided valuable information to women with epilepsy.
"We have known for some time that valproic acid [valproate], when taken during pregnancy, is associated with an increased risk for birth defects," said Dr. Keith Eddleman, director of obstetrics at Mount Sinai Hospital in New York City. "Due to these increased risks, women with epilepsy who are contemplating pregnancy are more frequently being given levitiracetam -- with very little information available about its effect on the developing fetus."
He said this "study is important in that it is the first significant study to compare levitiracetam to valproic acid and shows that levetiracetam has a lower risk for developmental problems down the road."
Dr. Cynthia Harden is director of North Shore-LIJ's Comprehensive Epilepsy Care Center in Manhasset, N.Y. She called the report "reassuring" for women who rely on levitiracetam to control their seizures.
The study is also valuable in "confirming what is known regarding valproate as having the most risk for pregnancy outcomes," she said. "This carefully performed study focusing on levetiracetam impacts the well-being of many women and children affected by epilepsy and helps physicians to appropriately counsel mothers with epilepsy."
Shallcross added that, "it is very important that women do not stop taking their medication before speaking to their health care professional."
The study was funded by drug maker UCB Pharma, which makes Keppra. The findings appear in the Jan. 8 online issue of the journal Neurology.
Find out more about the use of epilepsy medications during pregnancy at the Epilepsy Foundation.