This latest research on the effects of sodium valproate was based on the findings on a study of 375 children born to mothers with confirmed epilepsy in Liverpool and Manchester.

All but 80 of the children had been exposed to anti-epilepsy drugs (AEDs) while in the womb: in 41 cases this was sodium valproate and in 52 it was carbamazepine. A further 21 children had been exposed to phenytoin, and the mothers of 49 children had taken a mixture of drugs to control their epilepsy.

The children whose mothers had taken valproate alone had, according to the researchers, an IQ "in the low average range" and one that was significantly lower - an average of seven points lower - than would have been expected. A verbal IQ score of 69 or below was more than three times as likely in children exposed to valproate alone compared with those children whose mothers had not taken any AEDs.

Frequent seizures by the mother during pregnancy were also significantly associated with a lower verbal IQ.

Dysmorphic features (birth defects and developmental delays) were more common among children whose mothers had taken valproate in pregnancy, affecting 44 per cent, compared with nine per cent of those whose mothers had taken carbamazepine, and two per cent among those whose mothers had not taken any AEDs while pregnant. There was a strong link between the degree of dysmorphism and the likelihood of significantly lower IQ.

The study's authors acknowledge that valproate is very effective at controlling seizures in specific types of epilepsy. However, they conclude that the results of their study are of concern given that valproate was first licensed in the United Kingdom in 1975. They add that several new drugs have come on the market since then:

“It is essential that adequately controlled prospective studies are established now to identify the level of risk for cognitive impairment in children of women taking both new and established [anti-epileptic drugs] during pregnancy."

A spokesman for Epilepsy Action commented on the findings:

“There is growing evidence that anti-epileptic drugs may increase the risks to the unborn child, particularly some of the older anti-epileptic drugs.

"However, seizure control is of paramount importance, particularly during pregnancy. Epilepsy Action is urging all women with epilepsy to seek pre-conception counselling before planning a family so they can discuss the options open to them, with the aim of achieving good seizure control whilst posing the minimum risk to the unborn child.

"Under no circumstances should women stop taking epilepsy medication without consulting their doctor or epilepsy specialist as this could be potentially harmful to their health and their unborn child.”

Epilepsy Action News

People with epilepsy should never discontinue anti-epileptic medications or make changes in activities unless specifically advised to do so by an attending physician.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others and use this medication only for the condition prescribed.