Pregnancies were collected in the German MS and pregnancy registry. We analyzed clinically relevant relapses (treated with high-dose glucocorticosteroids) during pregnancy and postpartum in a cohort stratified by timing of last anti-CD20-antibody infusion before pregnancy (6-12 months, 3-6 months, <3 months)) and number of infusions (>= 2 full cycles, <= 1 full cycle).

We identified 192 pregnancies (ocrelizumab: 160, rituximab: 32) with >=3 months postpartum follow-up. Most women (107/192: 55.7%) received the last infusion <3 months, 33.9% (65/192) 3-6 months, and the remaining 10.4% (20/192) 6-12 months prior to pregnancy. 25.5% (49/192) had a therapy duration <6 months. Only few women experienced relapses during pregnancy (4/192, 2.1%), or within 3 months postpartum (10/192, 5.2%). Pregnancy relapses were comparable between groups (6-12 months: 4.5% (1/22); 3-6 months: 1.5% (1/65); <3 months: 2.6% (3/115, p-value: 0.55), whereas only one woman (1/143: 0.7%) with >=2 full cycles experienced a pregnancy relapse, in contrast to three women with <=1 full cycle (3/49: 6.1%, p-value: 0.05). 

During the first 30 days postpartum 32/192 (16.7%) started a DMT, mainly anti-CD20-antibodies (29/32: 90.6%). Postpartum relapses ranged from 14.3% (3/21; last infusion 6-12 months before pregnancy) to 2.8% (3/106; last infusion <3 months before pregnancy, p-value: 0.07). Updated information will be presented at the meeting.