Cesarean sections prior to 39 weeks among pregnant patients with multiple sclerosis.

BACKGROUND: Pregnant women with multiple sclerosis have higher Cesarean section (C-section) rates than controls. Whether these are occurring prior to 39 weeks' gestation is unclear and important, as C-sections <39 weeks are associated with increased neonatal morbidity and are not recommended unless medically indicated. OBJECTIVES: Determine whether pregnant women with multiple sclerosis experience higher rates of non-medically indicated C-sections <39 weeks and whether these were attributed to multiple sclerosis. METHODS: We conducted a retrospective, population-based case-control study of pregnancies ⩾20 weeks' gestation among pregnant women with multiple sclerosis and 2:1 matched controls (1 January 2009-30 June 2024). Electronic health records identified C-sections <39 weeks and were manually reviewed for outcomes and covariates. RESULTS: Among 600 MS pregnancies and 1199 controls, C-sections <39 weeks were more frequent in pregnant women with multiple sclerosis (15.2% vs 9.8%, p = 0.0007). However, non-medically indicated C-sections <39 weeks were uncommon and did not differ significantly between groups (pregnant women with multiple sclerosis 3.7% vs controls 2.8%, p = 0.3386). The higher proportion of medically indicated C-sections <39 weeks in pregnant women with multiple sclerosis (11.5% vs 6.9%, p = 0.001) was driven by high-risk myomectomy and stalled labor. Multiple sclerosis was documented as a pregnancy complication in 24.2% of cases. CONCLUSIONS: C-sections <39 weeks were more common in pregnant women with multiple sclerosis but were attributable to standard obstetric indications rather than multiple sclerosis. Documentation of multiple sclerosis as a pregnancy complication suggests persistent provider misconceptions.