Perinatal outcomes in women with multiple sclerosis exposed to disease-modifying drugs

Background: The incidence of disease-modifying drug (DMD) exposure during pregnancy in multiple sclerosis (MS) is unknown and limited data exists regarding the potential harm of DMD exposure during pregnancy. Objective: To investigate the incidence and effect of in utero DMD exposure on perinatal outcomes. Methods: We conducted a retrospective analysis by linking two provincial, population-based databases, the British Columbia (BC) MS database with the BC Perinatal Database Registry. Delivery (duration of the second stage of labor, assisted vaginal delivery and Cesarean section) and neonatal (birth weight, gestational age, 5-minute Apgar score and congenital anomalies) outcomes were compared between women exposed and unexposed to a DMD within 1 month prior to conception and/or during pregnancy. Findings were reported as odds ratios (ORs) with 95% confidence intervals (CIs). Results: In all, 311 women with relapsing-remitting MS delivered 418 singleton babies between April 1998 and March 2009. 21/101 (21%) of births to MS women treated with DMD prior to pregnancy were exposed to a DMD. In all cases, exposure was documented as unintentional and DMD treatment was stopped within 2 months of gestation. The overall incidence of exposure was 21/418 (5%). DMD exposure was associated with a trend towards a greater risk of assisted vaginal delivery compared to the DMD naive groups (OR = 3.0; 95% CI: 1.0-9.2). All other comparisons of perinatal outcomes were unremarkable. Conclusion: The incidence of DMD exposure was relatively low and no cases were intentional. Further studies are needed to ascertain the safety of DMD exposure during pregnancy in MS.