Pregnancy and multiple sclerosis: a longitudinal study of 125 remittent patients.

The relationship between pregnancy and multiple sclerosis (MS) was assessed in a clinic-based, prospectively followed, population of 125 patients with a remittent onset of MS who had been followed for a mean (SD) of 10.3 (0.1) years. Thirty three women had a total of 49 pregnancies of which 32 had been full term and 17 terminated. There was a three-fold increase in the relapse rate per year during the first three months following delivery, compared with the baseline period of the same patients [1.62(0.38) vs 0.51(0.08) p = 0.05]. During pregnancy itself, the relapse-rate was not different from baseline. The overall relapse rate of the pregnancy group was lower than that of a control group without pregnancies after MS onset, but similar to that of patients who had children after MS onset, but no pregnancy during follow up. Pregnancy did not lead to increased disability. These results confirm that post partum increase in relapse rate is the main event related to pregnancy in MS and underline the difficulties of undertaking prospective studies in this field.