Newer-Generation Antiepileptic Drugs and the Risk of Major Birth Defects

CONTEXT: Epilepsy during pregnancy is a therapeutic challenge. Since the 1990s, the number of licensed antiepileptic drugs has substantially increased, but safety data on first-trimester use of newer-generation antiepileptic drugs and birth defects are limited. OBJECTIVE: To study the association between fetal exposure to newer-generation antiepileptic drugs during the first trimester of pregnancy and the risk of major birth defects. DESIGN, SETTING, AND PARTICIPANTS: Population-based cohort study of 837,795 live-born infants in Denmark from January 1, 1996, through September 30, 2008. Individual-level information on dispensed antiepileptic drugs to mothers, birth defect diagnoses, and potential confounders were ascertained from nationwide health registries. MAIN OUTCOME MEASURES: Prevalence odds ratios (PORs) of any major birth defect diagnosed within the first year of life by fetal exposure to antiepileptic drugs. RESULTS: Of the 1532 infants exposed to lamotrigine, oxcarbazepine, topiramate, gabapentin, or levetiracetam during the first trimester, 49 were diagnosed with a major birth defect compared with 19,911 of the 836,263 who were not exposed to an antiepileptic drug (3.2% vs 2.4%, respectively; adjusted POR APOR, 0.99; 95% confidence interval CI, 0.72-1.36). A major birth defect was diagnosed in 38 of 1019 infants (3.7%) exposed to lamotrigine during the first trimester (APOR, 1.18; 95% CI, 0.83-1.68), in 11 of 393 infants (2.8%) exposed to oxcarbazepine (APOR, 0.86; 95% CI, 0.46-1.59), and in 5 of 108 infants (4.6%) exposed to topiramate (APOR, 1.44; 95% CI, 0.58-3.58). Gabapentin (n = 59) and levetiracetam (n = 58) exposure during the first trimester was uncommon, with only 1 (1.7%) and 0 infants diagnosed with birth defects, respectively. CONCLUSION: Among live-born infants in Denmark, first-trimester exposure to lamotrigine, oxcarbazepine, topiramate, gabapentin, or levetiracetam compared with no exposure was not associated with an increased risk of major birth defects.