Influence of Intestinal Microbiota Implantation in Preterm Infants on Microbiota and Immune Orientation at 3 Years

Inclusion Criteria: * The parents of the patient (or legal guardian if any) have been informed about the implementation of the study, its objectives, its constraints, and patient rights * The parents of the patient (or legal guardian if any) must have given their free and informed consent and signed the consent form * The patient must be affiliated with or beneficiary of a health insurance plan * Premature infants born at less than 33 weeks of gestation Exclusion Criteria: * The patient is participating in another interventional study (Excepted " Recherche du Portage de Clostridium butyricum et de Toxines de Clostridium chez les Prématurés Hospitalisés en Néonatologie afin de prédire la survenue d'Entérocolites Nécrosantes", RCB 2016-A00-529-42 ; " BetaDose Dose reduction of antenatal betamethasone given to prevent the neonatal complications associated with very preterm birth ", RCB 2016-001486-90. * It is not possible to correctly inform the parent (or legal guardian, if applicable) * A serious deformity or digestive malformation was diagnosed at birth * During the hospital stay in the neonatology department, the patient had a digestive disease requiring surgery (except necrotizing enterocolitis) * A transfer to another hospital is foreseen/predictable (eg, due to geographical distance)