A new analysis of registry data from European countries does not support an association between prenatal exposure to lamotrigine monotherapy and risk of orofacial cleft and clubfoot, in contrast to signals from previous studies of the antiepileptic drug. The analysis was published online ahead of print April 6 in Neurology.
Helen Dolk, DrPH, Professor of Epidemiology and Health Services Research and Head of the Center for Maternal, Fetal, and Infant Research at the University of Ulster in Coleraine, Northern Ireland, and her colleagues analyzed data from 10.1 million births exposed to antiepileptic drugs, including lamotrigine as a monotherapy, during the first trimester between 1995 and 2011. The births were recorded in 21 population-based registries from 16 European countries. The outcomes of interest were major congenital malformations in general, as well as orofacial clefts and clubfoot.
Helen Dolk, DrPH
Assessment of all antiepileptic drug-exposed congenital malformation registrations revealed that 12% of pregnant registrants were exposed to lamotrigine monotherapy. An additional 7% were exposed to lamotrigine as part of polytherapy. A total of 77.1% of pregnant women exposed to lamotrigine monotherapy had a diagnosis of epilepsy. The proportion of lamotrigine monotherapy exposures increased during the study period.
A total of 147 babies exposed to lamotrigine monotherapy with congenital malformations not attributable to chromosomal irregularities were identified from the total sample. The odds ratio for having a child with orofacial clefts after exposure to lamotrigine monotherapy was 1.31. Based on these data, the authors estimated that exposure to lamotrigine would result in orofacial clefts in fewer than one in every 550 exposed babies.
The odds ratio for having a child with clubfoot after exposure to lamotrigine monotherapy was 1.83. Although the study results confirmed the statistically significant signal for an overall excess risk of clubfoot found in a previous study that analyzed births during 1995–2005, the investigators could not reproduce this result in an independent study population of 6.3 million births during 2005–2011. Lamotrigine monotherapy was not associated with significant differences in the risk for developing any other congenital malformations, the investigators said.