The prescribing of antiepileptic drugs for pregnant Australian women

Abstract

BACKGROUND: It is not clear how widely it is appreciated in Australia that certain antiepileptic drugs, particularly valproate, are teratogenic. AIM: The aim of the study is to assess trends in the pattern of antiepileptic drug prescribing for pregnant women in Australia to determine whether drug use is optimal, particularly from the fetal viewpoint. METHODS: Analysis of data contained in the Australian Register of Antiepileptic Drugs, assessing trends in antiepileptic drug use correlated with pregnancy outcomes. RESULTS: Valproate was the only significant teratogen among the antiepileptic drugs in common use. There was a fetal malformation rate of 14.5% associated with its use in monotherapy, as compared with a rate of 3.15% in antiepileptic drug-unexposed pregnancies in women with epilepsy (OR = 5.23, 95% CI = 1.81, 15.09). The highest malformation rate associated with any other antiepileptic drug used in monotherapy was 5.0%, for carbamazepine. Neurologists had progressively prescribed valproate less frequently and in lower dosage than other classes of practitioner over the 10-year study period, with a parallel decrease in occurrence of fetal malformations in pregnancies referred to the Register. Other prescribers of valproate did not seem to have adopted these practices to the same extent and had not obtained similar degrees of reduction in the occurrence of fetal malformations. CONCLUSIONS: Contemporary Australian obstetricians, even though they may not be valproate prescribers, when managing pregnancies in women taking valproate, need to be alert to the possibility that it may not be being used optimally from the fetal point of view, especially when not prescribed by neurologists.