Lamotrigine and the risk of malformations in pregnancy

Abstract

The article regarding lamotrigine and the risk for pregnancy malformations by Cunnington et al. provides encouraging information for women with epilepsy and their families1 but their conclusion that “the risk of all major birth defects after first trimester exposure to lamotrigine monotherapy (2.9%) was similar to that in the general population” may be exaggerated. Population comparisons for these estimates are problematic. The authors use as a population comparison data from the Metropolitan Atlanta Congenital Defects Program (MACDP) between 1991 and 1995.2 This population-based registry uses active case identification from multiple sources, undertakes direct chart review of potential cases, and includes all malformations identified through age 5. MACDP reports a malformation prevalence of 3.2%. To provide a better comparison with registry data such as that provided in the report of Cunningham et al., MACDP provides a prevalence of “early diagnoses” of malformations (presumably those readily identifiable at or shortly after birth) of 2.2%. Both of these prevalence rates include children with chromosomal and genetic anomalies—a group appropriately excluded from the Lamotrigine Registry data.1 A more appropriate comparison for birth prevalence of malformations may be that …