Infants with major malformations bom to 791 women who had taken lamotrigine as monotherapy during the first trimester of pregnancy, and had enrolled in the North American AED Pregnancy Registry, were identified in a study at the Genetics and Teratology Unit, MassGeneral Hospital for Children, Boston, and Boston University School of Medicine, MA. Of 684 lamotrigine-exposed infants included, 16 (2.3%) had major malformations identified at birth. Five (7.3/1000) had oral clefts: isolated cleft palate (3), isolated cleft lip (1), and cleft lip and palate (1). In comparison, the prevalence of isolated oral clefts in 206,224 unexposed infants bom at Brigham and Women's Hospital, Boston, was 0.7/1000 and one tenth that of exposed infants. Of infants enrolled in 5 other registries, 1,623 were exposed to lamotrigine, as monotherapy, and 4 had oral clefts, a prevalence of 2.5/1000. 
COMMENT. Infants exposed to the anticonvulsant lamotrigine during the first trimester of pregnancy have an increased risk of an isolated cleft palate or cleft lip deformity.