Prospective Twin Pregnancy Cohort at Montpellier University Hospital

Mother's inclusion Criteria: * Patient of legal age (≥ 18 years) * Patient pregnant with a twin pregnancy ≥ 25 weeks of gestation * Pregnancy initially twin, triplet, or quadruplet, progressing to a twin pregnancy after spontaneous or medical embryo reduction, or after selective termination of pregnancy * Delivery planned at Montpellier University Hospital Twins' inclusion Criteria: * Twins born in a twin pregnancy ≥ 25 weeks of gestation Mother's exclusion Criteria: * Pregnant woman with at least one fetus presenting with a chromosomal or genetic abnormality or a polymalformative syndrome, and for whom early postnatal death is anticipated. * Planned travel preventing the study from being completed * Failure to obtain informed and written consent from the patient for participation in the study and the collection of biological samples * Patient unable to read and/or write French * Patient unable to understand and/or speak French * Patient not benefiting from a national health insurance scheme * Person under legal protection, guardianship or curatorship * Person participating in other interventional research study Twins' exclusion Criteria: * Mother's absence from or withdrawal from the study * Birth in a facility other than Montpellier University Hospital * One or two children under guardianship * Lack of informed and written consent from legal representatives * One of the two fetuses is expected to die * Lack of informed and written consent from the prospective parent(…