Since multiple sclerosis (MS) is often diagnosed in young women, pregnancy is a common topic for women with MS (wwMS). The study aimed to assess the measurement properties of two patient-reported outcome measures on motherhood choice in MS, and to explore the information and support needs of wwMS concerning motherhood. We conducted an anonymous web-based survey to validate the motherhood/pregnancy choice and worries questionnaire (MPWQ, 31 items plus up to 3 additional items) and the motherhood choice knowledge questionnaire (MCKQ, 16 items). We used mailing lists and social media for nationwide recruitment in Germany, and included women of childbearing age with relapsing-remitting MS, clinically isolated syndrome or suspected MS who were considering pregnancy or were pregnant. For the MPWQ, we assessed item difficulty, discriminatory power, and internal consistency (Cronbach's alpha; CA). We analysed construct validity using the Leipzig Questionnaire of Motives to have a Child, the Decisional Conflict Scale, the Hospital Anxiety and Depression Scale, and the Pregnancy-Related Anxiety Questionnaire-revised2. We studied the structural validity using exploratory factor analysis (EFA). The MCKQ was evaluated descriptively. We explored the information and support needs of wwMS on motherhood descriptively. We examined correlations between MCKQ, MPWQ and clinical characteristics and performed exploratory group comparisons considering the following binary variables: having children and being pregnant. 325 wwMS started the survey; 232 wwMS met our inclusion criteria and were analysed. Their mean age was 30 years (SD 5). Most women had relapsing-remitting MS (n=218; 94%), 186 (80%) had no children, and 38 (16%) were pregnant. Internal consistency was good for the worries subscale (CA>0.8), while it was unsatisfactory for the attitude and coping subscales (CA<0.7). The EFA did not support the three-scale structure (coping, attitude, and worries). Due to these findings, we decided to keep the worries scale without any subscale. The items from the coping scale and attitude scale could be assessed as additional descriptive items. Convergent and divergent construct validity of the MPWQ was satisfactory. 206 wwMS (89%) completed the MCKQ. On average, 9 of 16 (56%) items were answered correctly (range 2-15), and the questionnaire showed a good balance between easy and difficult items. Questions on immunotherapy, disease activity, and breastfeeding were the most challenging. WwMS were confident in getting pregnant and raising a child (n=222; 96%). Most wwMS were worried about postpartum relapses (n=200; 86%) and the long-term effects of pregnancy on disease evolution (n=149; 64%). About half of the wwMS (n=124; 54%) did not know where to find professional help and 127 (55%) had no strategies to cope with future impairments so that they could take care of a child. Our results support the suitability and acceptability of both questionnaires as potential patient-reported measures for assessment of knowledge and worries around motherhood/pregnancy in MS. The survey results highlight the need for evidence-based information on motherhood in MS to increase knowledge, reduce worries and support wwMS in making informed decisions.