Widely reported this month are new results from a major collaborative study of the effects of taking anti-epileptic drugs (AEDs) during pregnancy on cognitive ability. In a presentation at the American Academy of Neurology's 59th Annual Meeting in Boston last month, Dr Kimford Meador focused on the effect of four AEDs (carbamazepine, lamotrigine, phenytoin and sodium valproate) taken during a mother's pregnancy on the ability of their children to think and learn.

A total of 187 children, now aged two years, were included in this analysis. Their mothers have epilepsy and were taking one AED to control their seizures during their pregnancy. The researchers measured the children's IQ, having also measured the IQ of their parents for comparison.

The study found that children of mothers who took lamotrigine had an average IQ of 96 points; carbamazepine- and phenytoin-exposed children had an average of 93 points; and valproate-exposed children 84 points. Nearly a quarter (24%) of the children exposed to valproate had IQs less than 70 points (considered to amount to mental retardation), compared with 12% for carbamazepine- and phenytoin-exposed children and 9% for lamotrigine-exposed children. (These results were weighted to take into account parents' IQ levels and the size of the dose the mother was taking.)

The Neurodevelopmental Effects of Antiepileptic Drugs (NEAD) study is still ongoing in 25 epilepsy centres in the UK and US. It will follow children born to mothers with epilepsy until they are six. It as already reported the rates of "major adverse outcomes", that is miscarriage and major physical disabilities, associated with these drugs. Read Epilepsy Research UK's article about these results.

The NEAD study aims to find out how much each AED has the potential to damage a baby's cognition and development, so as to recommend the least harmful treatment. The risk of AEDs' damaging the baby must however be balanced against the risk of the mother's having seizures, which could themselves hurt the baby.

The authors of this study recommend that sodium valproate should not be the first choice of treatment for women of childbearing age. (Other studies of taking AEDs during pregnancy have made the same recommendation.) Nevertheless, they acknowledge that it is an extremely effective drug, especially for treating generalised epilepsies (recently confirmed by the SANAD study, reported here) and
should continue to be used, though at the lowest possible dose.

If you are a woman of child-bearing age taking an AED, and are concerned about a pregnancy, planned or current, Epilepsy Research UK recommends that you book an appointment with your consultant for a discussion. For more information, we recommend the information pages here and here.

Read more here and here