FRIDAY, Dec. 3 (HealthDay News) -- Pregnant women with epilepsy who are taking carbamazepine (Tegretol) to control seizures may be at a slightly increased risk of having an infant with spina bifida, a new study finds.

Spina bifida is a condition in which the bones of the spine do not close but the spinal cord remains in place, usually with skin covering the defect. Most children will need lifelong treatment for problems arising from damage to the spinal cord and spinal nerves.

"For women with epilepsy, seizure control during pregnancy is very important," said lead researcher Lolkje de Jong-van den Berg, from the division of pharmacy at the University of Groningen in the Netherlands. "Our study can help in decisions regarding whether carbamazepine should be the drug of choice in pregnancy."

However, the best option regarding treatment can be chosen only on an individual basis by the woman and her neurologist before pregnancy, weighing the benefits of epilepsy control against the risk of birth defects, de Jong-van den Berg said.

The report is published in the Dec. 3 online edition of the BMJ.

For the study, de Jong-van den Berg's team reviewed existing research to determine the risk of birth defects among women taking Tegretol.

The researchers found that infants of women taking Tegretol were 2.6 times more likely to have spina bifida, compared with women not taking any anti-epileptic medication.

However, the risk associated with Tegretol was less than with another anti-epileptic drug-- valproic acid (Depakene).

In fact, Tegretol was less risky than valproic acid when it came to other birth defects such as hypospadias, where a boy's urinary opening develops in the wrong part of the penis or in the scrotum.

"Carbamazepine is specifically related to an increased risk of spina bifida," de Jong-van den Berg said. "But you have to keep in mind that the absolute risk is small."

For Tegretol taken in the first trimester, the overall risk of a major malformation was 3.3 percent, the study authors reported.

The same group of researchers found in another study, published this year in the New England Journal of Medicine, that women taking valproic acid were six times more likely to have an infant with spina bifida and seven times more likely have an infant with hypospadias, compared with women using other anti-epileptic drugs.

The researchers agree with a recommendation from the American Academy of Neurology that valproic acid should be avoided in pregnancy if possible.

Dr. Orrin Devinsky, director of the Epilepsy Center at NYU Langone Medical Center, said that "for women of childbearing age, these drugs represent a risk."

Women need to balance the risk and benefit of these drugs, he explained. Women with epilepsy need to stay on an anti-epileptic drug while they are pregnant, Devinsky said.

"The risk of seizure to themselves and potentially to their fetus is greater than the risk of anti-epileptic drugs," he added.

There are alternative drugs, specifically lamotrigine (Lamictal) and levetiracetam (Keppra). However, there is little data on any dangers associated with these drugs during pregnancy, Devinsky noted.

Another expert, Dr. Kimford Meador, a professor of neurology at Emory University School of Medicine, said women need to know the risks associated with Tegretol.

"If a woman is of childbearing potential and you are prescribing this drug, that's when the conversation needs to occur," Meador said.

More information

For more information on epilepsy, visit the U.S. National Library of Medicine.