Background: Counseling on pregnancy is still challenging, particularly regarding the use of disease-modifying treatments (DMTs). We are lacking long-term outcomes in children exposed to DMTs., Objectives: This study aimed to set up a French pregnancy registry for women with multiple sclerosis (MS) and related disorders nested within the Observatoire Français de la Sclérose en Plaques (OFSEP) cohort., Methods: Prospective, observational, multicentric, epidemiological study in France. Neurological visits are organized according to routine practice. Data are collected on the OFSEP minimal datasheet. Auto-questionnaires on pregnancy are completed by patients at Months 5-6 and 8 during pregnancy, and Months 3, 6, and 12 postpartum. A specific survey on analgesia is completed by anesthesiologists. Pediatric data are collected from the child's health book, where visits on Day 8, Month 9, and 24 are mandatory. Parents complete neurodevelopmental questionnaires at Year 1, Years 2 and 6., Results: The RESPONSE study started in August 2019. On 7 April 2023, 515 women were included. Baseline demographics are presented., Conclusions: RESPONSE will provide rich information on the global management of pregnancy in France and prospective data on children until the age of 6 years, exposed or not to a DMT, including data on neurodevelopment that can be compared to the general population., Study Funding: EDMUS and ARSEP Foundation, Biogen, Roche., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: S.V. has received consulting and lecturing fees, travel grants, and unconditional research support from Biogen, Janssen, Merck, Novartis, Roche, Sandoz, and Sanofi. B.B. has received consulting and lecturing fees, travel grants, and unconditional research support from Alexion, Biogen, Horizon, Janssen, Merck, Novartis, Roche, Sandoz, and Sanofi. R.C. has no financial disclosure to declare. K.D. has received consulting and lecturing fees, travel grants, and consulting fees for advisory boards from Alexion, Biogen, Horizon, Novartis, Roche, and Sanofi. A.M.G. has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen, Novartis, Merck, Sanofi, and Roche. F.R. and C.L.F. have no financial disclosure to declare. E.L. has received consulting and lecturing fees, and travel grants from Alexion, Merck, Novartis, Roche, and Sanofi. L.B. and C.G. have no financial disclosure to declare. R.M. has received personal fees from Horizon Therapeutics, Alexion, Roche, and UCB and non-financial support from Horizon Therapeutics, Merck, Biogen, and Roche, outside the submitted work. E.M. reports research support from Biogen and ARSEP foundation and personal fees for lectures and advisory boards from Biogen, Janssen, Merck, Novartis, Roche, Sanofi, and Teva.