Women who take one of the most common drugs to treat epilepsy face an increased risk of having a baby with spina bifida, researchers warn today.
A study published by the British Medical Journal online reveals that spina bifida was the only specific major congenital malformation that was significantly associated with exposure to carbamazepine – although it stresses that the overall risk is still low.
A review of all published studies to identify specific major malformations linked with carbamazepine use in the first three months of pregnancy was undertaken by Professor Lolkje de Jong-van den Berg from the University of Groningen in the Netherlands, and colleagues.
They found the overall risk of the foetus developing a major malformation in the first three months was 3.3 per cent if the mother took carbamazepine. Spina bifida was 2.6 times more likely in infants of women who had taken it compared with those who did not take antiepileptic drugs.
However, the risk was still smaller for carbamazepine than for valproic acid.
An earlier study on valproic acid, published in the New England Journal of Medicine earlier this year, said that women on valproic acid were six times more likely to have infants with spina bifida compared with women using other antiepileptic drugs.
The research team concurred with the American Academy of Neurology, which recommended that women should avoid valproic acid in pregnancy if possible.
“Although most antiepileptic drugs taken during pregnancy significantly increase the risk for one or more specific congenital malformations, the occurrence of these malformations is nevertheless rare and most exposed pregnancies result in a baby without malformation,” they add.
Writing in the same journal, Irena Nulman, Associate Professor of Paediatrics at the University of Toronto, Canada, says carbamazepine should be considered the drug of choice in pregnancy because it was associated with the lowest rate of morphological defects.
Discontinuing antiseizure drugs was not an option for many women, she said. Women should plan their pregnancy, receive evidence-based prenatal counselling, and be given the safest antiepileptic drug, concluded Professor Nulman.
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