To determine whether pregnant women with MS (pregMS) experience higher rates of non-medically indicated Cesarean sections (C-section) prior to 39 weeks’ gestation (<39w) and whether these were attributed to MS or obstetric indications.

Though MS is not an indication for C-section, PregMS have higher C-section rates compared to age-matched controls. Whether these are occurring <39w is unclear and important because C-sections <39w increase risks of adverse neonatal outcomes and are not recommended according to obstetric guidelines unless medically indicated.

We identified 600 pregnancies among women with MS and 1199 among controls. C-sections <39w were more frequent in MS pregnancies (n=91, 15.2% MS and n=117, 9.8% controls, p=0.0007). Non-medically indicated C-sections <39w were uncommon and similar between groups (n=22, 3.7% MS and n=34, 2.8% controls, p=0.3386). Among women with C-sections <39w, pregMS were more likely to have a mental health condition (27.5% MS and 2.8% controls) and less likely to have diabetes at pregnancy start. Demographics and comorbidities were otherwise comparable. MS was documented as a pregnancy complication in 24.2% of cases (n=22).The higher proportion of medically indicated C-sections <39w in pregMS (n= 69, 11.5% MS and n=83, 6.9% controls, p=0.001) was driven by more high-risk myomectomies (n=10, 1.7%, p=0.0008) and stalled labor (n=16, 2.7%, p=0.0021) compared to controls (0.3% and 1.4%, respectively).

These findings are reassuring for women with MS planning pregnancies. Though MS was documented as a pregnancy complication in nearly one-quarter of pregMS, suggesting possible lingering misconceptions among obstetric providers, this did not result in substandard obstetrical care.