Relapse Patterns in MS Patients During Pregnancy and Postpartum

A retrospective, observational study of relapse patterns in women with MS who took disease-modifying therapies (DMT) either before or during pregnancy and postpartum found that the proportion of women experiencing moderate/severe relapses declined during pregnancy (from 8.7% pre-pregnancy to 1.1% in trimester 3). Relapses increased postpartum, especially in 0 to 3 months postpartum compared with 4 to 6 months postpartum (6.5% vs 5.4%, respectively). In addition, in those who stopped DMT during pregnancy, the risk of postpartum relapse was higher in those who did not reinitiate DMT postpartum compared with those resuming DMT (10.9% vs 5.2%, respectively).  

The study analyzed data from the US MarketScan Commercial and Medicaid claims databases for female patients who had ≥ 1 insurance claim submitted under the diagnosis code of MS from January 2016 to April 2021. In this study, moderate-to-severe relapse was defined as MS-related hospitalization or an outpatient visit and 1 claim within 7 days of the visit with steroids or total plasma exchange. A total of 944 patients (mean [SD] age, 32.4 [5.0] years) were eligible for the study (commercial, n=688; Medicaid, n=256). Overall, the number of patients with any moderate-to-severe relapse declined over pregnancy (from pre-pregnancy, n=82 [8.7%]; trimester 1, n=11 [1.2%]; trimester 2, n=8 [0.9%]; trimester 3, n=10 [1.1%]) but increased postpartum.

More relapses were experienced 0-3 months postpartum (n=61 [6.5%]) compared to 4-6 months postpartum (n=51 [5.4%]). Of the 889 patients who stopped DMT for pregnancy, the risk of postpartum relapse was lower in women who resumed DMT postpartum (10/192) than in patients who did not (76/697) (5.2% vs 10.9%, P=0.018). Re-initiation of DMT during the postpartum period was associated with lower risk of relapses.

Study results were shared in a poster at the recent Americas Committee for Treatment & Research in Multiple Sclerosis (ACTRIMS) Forum 2023.