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J Med Genet 39:243-244 doi:10.1136/jmg.39.4.243
  • Commentary

Assessing epidemiological evidence for the teratogenic effects of anticonvulsant medications

  1. H Dolk1,
  2. P McElhatton2
  1. 1Department of Epidemiology and Health Services Research, Faculty of Life and Health Sciences, University of Ulster, Shore Road, Newtownabbey BT37 0QB, UK
  2. 2National Teratology Information Service (NTIS), Regional Drug and Therapeutics Centre, Wolfson Unit, Claremont Place, Newcastle upon Tyne NE2 4HH, UK
  1. Correspondence to:
 Professor H Dolk, Department of Epidemiology and Health Services Research, Faculty of Life and Health Sciences, University of Ulster, Shore Road, Newtownabbey BT37 0QB, UK;
 h.dolk{at}ulst.ac.uk

    Antiepileptic medication in pregnancy

    Epidemiological studies of pregnancy outcomes of women with epilepsy are important, primarily to inform choice of treatment options in clinical care of pregnant women and to inform counselling, the need for prenatal and postnatal screening, and the need for early medical, behavioural, or educational intervention.

    In this issue (251), Dean et al report on a long term follow up of the health and neurodevelopment of children exposed to antiepileptic drugs before birth. They did this by consulting obstetric records to identify mothers with epilepsy who delivered in a single maternity unit between 1976 and 2000, inviting mothers to participate in the study by letter via their primary care physicians, conducting an interview with participant mothers, and consulting a variety of medical and child health records. The oldest children in the study were 15 years of age.

    There is a fairly solid consensus that epilepsy in pregnancy treated with anticonvulsants is associated with an overall two- to three-fold increased risk of congenital malformation compared to the general population. The first challenge of the epidemiological approach is to mount sufficiently large studies. Since epilepsy is fortunately uncommon (6 per 1000 pregnancies or less), and since major congenital malformations are uncommon (2-3% of all births), every 10 000 pregnancies will yield only three or four cases of major congenital malformation born to epileptic women. Kallen,1 reviewing the results of 24 studies, indicated that nearly half of these studies included fewer than 150 infants born to epileptic mothers and did not have the statistical power to reveal a two- to three-fold raised risk of major malformation. It is generally necessary therefore to make a combined assessment of existing studies, particularly when assessing risks of specific anomalies. Schardein2 reviewed 17 cohort studies including a total of 2168 infants of …