Abstracts

To determine the relative risks for major congenital malformations (MCM) of in-utero exposure to anti-epileptic drus (AEDs). Prospective, observational, registration and follow-up study. Subjects are women with epilepsy who become pregnant, whether or not they are taking an AED, either singly or in combination, who are referred before the outcome of the pregnancy is known. The main outcome measure is MCM rate for each AED regime. MCM rate is defined as the total number of live-births with an MCM plus the the total number of pregnancy losses with an MCM, divided by the total number of live-births plus the total number of pregnancy losses with an MCM. Full outcome data are available on 2829 pregnancies, with 560 outcomes awaited. Monotherapy exposures account for 71.9% (MCM rate 3.7% [95% C.I. 3.0% - 4.6%]), polytherapy exposures for 21.0% (MCM rate 6.6% [95%C.I. 4.8 - 8.8%]), and no AED exposures for 7.1% (MCM rate 3.0% [95% C.I. 1.4 - 6.1%]). The crude MCM rate for carbamazepine [n=775] at 2.3% (95% C.I. 1.5 - 3.6%) is significantly less than for sodium valproate [n=619] at 6.0% (95% C.I. 4.4 - 8.1%). Although the crude MCM rate for lamotrigine [n=476] at 2.9% (95% C.I. 1.4 - 4.9%) is less than for sodium valproate the difference is not statistically significant. The UK Epilepsy and Pregnancy Register is proving an effective method of collecting outcome data on large numbers of pregnancies occurring in women with epilepsy. The results suggest there are differences in MCM rates between AEDs. Further cases are required to establish the degree of these differences and the influence of other confounding variables. (Supported by Epilepsy Research Foundation Grant, (and donations from Glaxo-Smith-Kline, UCB-Pharma, Janssen-Cilag, Sanofi-Synthelabo, Parke-Davis to maintain database, run epilepsy free-phone helpline, provide fliers).)