Monitoring of a cohort of premature newborns with constitution of a collection of biological samples.~follow-up of newborns from birth up to 37 weeks of amenorrhea. The medical care of children will not be affected by their participation in the research.~Sampling of amniotic fluid at the time of rupture of the water bag~Sampling of the blood contained in the umbilical cord after clamping and section of the cord~Sampling of meconium during the first 24 hours of life in intensive care / neonatal / maternity ward~Collection of a daily stool sample until the end of hospitalization and when a NEC occurs~Sampling of gastric residues during an episode of NEC~Taking a daily sample of the newborn's enteral food~Sampling of 500 µL of additional blood weekly during the punctures made for the treatment~Daily statement of constants~Record of all complications related to prematurity (HIV, bronchodysplastic, sepsis)~Blood analysis: CBC, platelets and CRP (data analyzed as part of the treatment). Specific analyzes for research will assess: the level of tryptase, IL4 and TLR4. The samples will be stored and analyzed in the immunology laboratory of the CHU Clermont Ferrand (Pr B. Evrard)~Analysis of the meconium sample and each stool emitted during hospitalization, and during an episode of ECUN
Compare the bacterial digestive microbiota during the stay in neonatal intensive care between a group of premature newborns developing a NEC (necrotizing enterocolitis) and a group of newborns free from NEC.