The influence of pregnancy on the course of multiple sclerosis (MS) has long been a controversial topic. After the publication of the first large prospective study of pregnancy and MS in 1998, counselling of women with MS has radically changed and many patients have been able to fulfill their desire of motherhood. However, there are still some challenges for the neurologist, who has to face old unanswered questions or new issues, regarding the use of disease modifying drugs (DMDs) in this period of life, effects on the short and long term outcome of the mother (in terms of relapses and disability) and the child, role of breast-feeding and locoregional analgesia.

To set up a national prospective pregnancy registry for patients with MS, nested within the Observatoire Français de la Sclérose en Plaque (OFSEP) cohort, owing to a better knowledge of interactions between MS and pregnancy-related issues (pregnancy itself, locoregional analgesia, breastfeeding, impact of using or stopping DMDs on women/children…)

METHODOLOGY Prospective, observational, multicentric and national epidemiological study, within the scope of the OFSEP, including all groups of patients eligible to participate in the Observatoire Français de la Sclérose en Plaque (OFSEP) (definite MS, radiologically isolated syndromes, clinically isolated syndromes, neuromyelitis optica (NMO) and NMO spectrum disorders), with no age limit and an ongoing pregnancy. Women will be followed during pregnancy and in the year after and their children until 6 years of age.

STATISTICAL ANALYSIS To be determined for each specific question. EXPECTED RESULTS Interactions between pregnancy and MS course have been well characterized before the therapeutic era. Neurologists and patients are lacking information to weigh benefits and risks of DMDs used immediately before or during pregnancy, including short and long-term risks to the mother and to the child, but also after delivery. This study should help provide better answers to those questions as well as to still controversial questions about locoregional analgesia and breastfeeding. By following these patients within the Observatoire Français de la Sclérose en Plaque (OFSEP) cohort, the investigator will also have access to a comprehensive description of MS before pregnancy but also in the long term.

Inclusion Criteria:

• All groups of patients eligible to participate to the Observatoire Français de la Sclérose en Plaque (OFSEP), including :
• Definite Multiple sclerosis (MS) according to McDonald criteria
• Whatever the clinical course (single attack MS, relapsing-remitting MS, secondary progressive MS, primary progressive MS)
• Radiologically Isolated Syndromes (RIS) (will be validated by the RIS expert group)
• Clinically Isolated Syndromes (CIS)
• Neuromyelitis optica (NMO) and NMO spectrum disorders (will be validated by the "Neuro-optico-myélite aiguë de Devic et des syndromes neurologiques apparentés" (NOMADMUS) expert group)
• No age limit (patients under the age of 18 might be included, provided informed consent is obtained from the parents)
• Ongoing pregnancy: there will be no limit in the gestational age at inclusion. Women can be included at any time before delivery, but the gestational age at inclusion will be recorded and introduced in the analyses whenever pertinent. However, neurologists and patients will be encouraged to start the study as soon as pregnancy is diagnosed.
• Able to give informed consent
• Able to read and/or understand French

Exclusion Criteria:

• None

Pregnant women with multiple sclerosis or related neurological syndromes