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New research into anti-epileptic medication effects on pregnant women

5 May, 2004

The preliminary
results of a five year study into the effects of anti-epileptic drugs
on fertility and the risk of birth defects in children born to women
with epilepsy have been presented to the American Academy of Neurology Annual Meeting.

Although
the majority of children born to mothers with epilepsy will be healthy,
previous research has shown that some of babies are at an increased
risk for birth defects or developmental delays.

In
this study, involving nearly 350 mother/child pairs, four of the most
commonly prescribed anti-epileptics drugs (AEDs) - carbamazepine,
lamotrigine, phenytoin and valproate - are being tested to determine if
they have a negative and lasting impact on the developing brains of
foetuses when mothers take them while pregnant. With over a year left
in the study to record and analyse the effects of the drugs,
researchers are already seeing significant data related to
complications with these medications. The percentages of children with
birth defects or developmental disabilities for each AED were:
carbamazepine 10 per cent, lamotrigine two per cent, phenytoin seven
per cent, and valproate 28 per cent.

Lead researcher Dr Page Pennell, associate professor of neurology at Emory University School of Medicine in Atlanta, said:

"Newborns of
women with epilepsy have a four to seven per cent risk of birth defects,
compared to the two to three per cent risk of the general population,
and we think some anti-epileptic medications may be to blame. While
the outcomes are many times positive, a small number of babies born
to epileptic mothers who took AEDs during pregnancy have congenital
heart defects, neural tube defects (spina bifida) or cleft lip and
palate.

"While
our numbers are still preliminary, we are learning that some of the
newer AEDs, like lamotrigine, cause less harm to the child, while it
looks like others cause more damage."

The researchers are also learning that effects of AEDs in offspring may not be so instant. Dr Pennell added:

"We are recognising that we need to not only be concerned about birth
defects from the AEDs, but also about cognitive effects later in the
child's life. At two years of age, we are realising some of these
children are experiencing speech delays, delays in walking and
difficulties with fine motor skills. This study should help us notice
the subtle differences in a child's ability to learn and it should help
us understand how to best care for pregnant women and their children."

The
researchers are expanding this study to examine how AEDs cross into the
foetus and exactly how much of the medications are absorbed. They also
hope to follow all children in the study until they are six-years-old.

Dr
Pennell added that women should always talk with their doctor before
becoming pregnant to discuss which treatment plan is best for them.