Pregnancy in women with MS: Impact on long-term disability accrual in a nationwide Danish Cohort.

BACKGROUND Pregnancy is considered to influence the disease course in women with multiple sclerosis (MS). OBJECTIVE The aim of this study was to investigate the effect of pregnancy on long-term disability accrual in women with MS. METHODS The Danish Multiple Sclerosis Registry (DMSR) was used to identify women diagnosed with clinically isolated syndrome or relapsing-remitting MS. Cox models with pregnancy as a time-dependent exposure and propensity score (PS) models were used to evaluate time to reach confirmed Expanded Disability Status Scale (EDSS) score of 4 and 6. RESULTS A total of 425 women became parous and 840 remained nulliparous. When including pregnancy as a time-dependent exposure, a non-significant association with time to reach EDSS 4 (hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.61-1.20) and EDSS 6 (HR 0.70, 95% CI 0.40-1.20) was found. Correspondingly, the PS model showed no association with pregnancy on time to reach EDSS 4 (HR 0.85, 95% CI 0.56-1.28). CONCLUSION This study concludes that pregnancy does not affect long-term disability accumulation.