(246) Changes in the Use of Carbamazepine Before, During and After Pregnancy: A Nationwide Study in France between 2013 and 2021

Background: Carbamazepine (CBZ) is an antiseizure medicine (ASM) mainly used to treat epilepsy. Continuous treatment of epilepsy during pregnancy is often required, as uncontrolled disease can have adverse effects. CBZ is an established teratogenic drug, and recent data suggest that in utero exposure may also expose to an increased risk of neurodevelopmental disorders. Few data are available on the frequency and types of treatment changes when a pregnancy occurs in women treated with CBZ, and on their evolution over time.

Objectives: To assess changes (discontinuation, switch) in the use of CBZ before, during and after pregnancy in France and their evolution over the period of 2013-2021.

Methods: We used data of the National Mother-Child EPI-MERES Register, built from the National Health Data System (SNDS) and covering 98% of deliveries in France since 2010. All pregnancies ended between 2013 and 2021 in women aged 15-49 years using CBZ 6 months before pregnancy were included. CBZ discontinuation before and during pregnancy was defined as no dispensation during a 70-day period after the last fill, and switch as initiation of another ASM within 70 days following CBZ last dispensation.

Results: Among a total of 1,577 pregnancies in women using CBZ 6 months before pregnancy (626 in 2013-2015, 507 in 2016-2018, 444 in 2019-2021), 30.0% were interrupted (elective/therapeutic abortion < 22 weeks: 29.4%, therapeutic abortion >=22 weeks: 0.6%). This rate increased from 25.7% in 2013-2015 to 31.1% in 2019-2021. Among uninterrupted pregnancies, CBZ discontinuation occurred in 58.0% and switch to another ASM in 4.6%, with proportions increasing from 49.6% in 2013-2015 to 70.1% in 2019-2021 for discontinuations, and from 3.6% to 6.3%, for switches. Discontinuation and switches mainly occurred prior to conception (66.8% and 51%, respectively). Most switches were to lamotrigine (55.2%), oxcarbazepine (15.5%), and levetiracetam (10.3%). Six months after pregnancy end most women used an ASM, either CBZ (59.1%) or a different one (8.0%). The use of CBZ 6 months after pregnancy end declined from 64.7% in 2013-2015 to 49.8% in 2019-2021, while the proportion of women using another ASM or no ASM increased (from 7.5% to 9.2% and from 27.8% to 41.0%, respectively).

Conclusions: Despite changes occurred over the last decade in the ASM treatment management of women on CBZ experiencing a pregnancy, efforts should be stepped up to further reduce the number of pregnancies exposed to CBZ.