Pregnancy in multiple sclerosis women with relapses in the year before conception increases the risk of long-term disability worsening.

Background: The influence of pregnancy on long-term disability in multiple sclerosis (MS) is still controversial.

Objective: To assess the risk of long-term disability worsening after pregnancy in MS women as compared with a propensity-score (PS) matched group of MS women without pregnancy.

Methods: In the setting of the Italian Pregnancy Dataset, MS patients with (pregnancy group (PG)) and without pregnancy (control group (CG)) were recruited. Time to disability worsening on the Expanded Disability Status Scale (EDSS) was assessed through a multivariable Cox regression model.

Results: The PS-matching retained 230 PG and 102 CG patients. After a follow-up of 6.5 +/- 3.1 years, disability worsening occurred in 87 (26.2%) women. In the multivariable analysis, disability worsening was associated with pregnancy in women with relapses in the year before conception (adjusted hazard ratio (aHR) = 1.74; 95% confidence interval (CI) 1.06-2.84; = 0.027), higher EDSS (aHR = 1.39; 95% CI 1.12-1.74; = 0.003), younger age (aHR = 0.95; 95% CI 0.91-0.99; = 0.022) and shorter DMD exposure over the follow-up ( < 0.008).

Conclusion: Pregnancy in MS women with relapses in the year before conception increases the risk of long-term disability worsening. Our findings underscore the importance of counselling in MS women facing a pregnancy that should be planned after a period of clinical stability, favouring treatment optimization in patients with recent disease activity.