Multiple sclerosis (MS) is a autoimmune disorder which preferentially affects young women of childbearing age. During pregnancy, the annualized relapse rate (AAR) is modified, but pregnancy has no harm effect on the long-term course of the disease. We aimed to study the clinical course of our MS patients during pregnancy, and compare their obstetrics outcomes with a control group of non-MS patients.A single centre prospective observational study was conducted. We assessed the reproductive history, MS history, pregnancy course and new-born outcome of a cohort of MS patients who had had a pregnancy between january 2007 and july 2012. We compared the global outcomes with a control cohort of 58 age-matched healthy pregnancies.Complete data from 35 consecutive women were analyzed, 40 deliveries. Control groups: 58 patients, 60 deliveries. EDSS at pregnancy 0,7. ARR before pregnancy 0,5. During pregnancy 0,3, after pregnancy 0,4. Twelve patients were on disease-modifying drugs (DMD) before pregnancy, 4 prenatal exposure occurs. The comparison between relapse rate and EDSS before, during and after delivery showed no statistically significant difference. In addition, compared to control group, there were also no differences in the obstetric outcomes. In MS cohort, we found a higher incidence of assisted reproductive treatments and lower breastfeeding rate, both statistically significant.Our series confirms that pregnancy has no negative long term impact on the progression of MS and also suggest that there is no additional morbidity in the pregnancy, comparing to the rest of the population. more...