Antieplileptic drug use and birth rate in patients with epilepsy -: a population-based cohort study in Finland

BACKGROUND: Antiepileptic medication use affects reproductive endocrine function, but its impact on fertility is not well known. METHODS: All epilepsy patients, who were approved as being eligible for reimbursement for antiepileptic drug (AED) costs from the Social Insurance Institution (SII) of Finland for the first time 1985-94, were identified from the SII database. A reference cohort without epilepsy was identified from the Finnish Population Register Centre. Information on AED purchases 1996-2000 was obtained from the SII database through computerized record linkage with the unique personal identification number assigned to all residents of Finland. The three AEDs included were carbamazepine, oxcarbazepine (OXC) and valproate. RESULTS: Birth rate was lower in both men and women with epilepsy on AEDs than in the reference cohort without epilepsy. However, compared with patients not using AED during the study period, the birth rate was lowered only among men on OXC [rate ratio (RR) = 0.52, 95 % confidence interval (CI) = 0.32, 0.84]. CONCLUSIONS: The birth rate was lower in both women and men on any of the three AEDs compared with the reference cohort without epilepsy. However, a statistically significant difference between treated and untreated patients was only seen in men on OXC. It is unclear to what extent the differences found in this study are due to social or biological factors.