Compare serum tryptase levels of premature babies (<37 weeks of amenorrhea) to children born at full term.

Study the evolution of serum tryptase levels in premature babies(<37 weeks of amenorrhea). Study the relationship between the onset of infectious complications, mainly the type of necrotizing enterocolitis seen in premature babies (<37 weeks of amenorrhea) and the evolution profile of serum tryptase levels.

It seems appropriate to believe that prematurity associated or not with a genetic-related sensitivity, involving several signaling pathways, makes children more vulnerable to different environmental, infectious factors that could trigger the different pathologies of premature babies. Mast cell, via its mediators, seems to play a key role.

Dosage of serum tryptase levels which is easily accessible and the work by Vitte let us imagine that the younger the child, the greater the mast cell expression, thus opening a capital pathway in the comprehension of immune system phenomena in premature babies and investigators can hope that by performing regular workups of serum tryptase levels, investigators could validate that some premature babies will express this activity in a more important manner. The relationship to eventual pathological phenomena such as necrotizing enterocolitis, but also bronchopulmonary dysplasia could then be highlighted.

Inclusion Criteria "Patients" :

• all premature babies (<37 weeks of amenorrhea)
• managed in the first 24 hours of life at the Reims university hospital
• parents accepted to participate in the research - social security card

Inclusion Criteria "Controls" :

• children born full term, just after each "patient" child included
• managed in the first 24 hours of life at the Reims university hospital
• parents accepted to participate in the research.

Exclusion Criteria "Patients" and "Controls"

• Not managed in the first 24 hours of life at the Reims University Hospital,
• Person, who has parental authority, protected by law,
• Newborns with a life and death emergency in the first 24 h of life,
• Person, who has parental authority, under age 18