Asthma newborn cohort/Exhaled Nitric Oxide as a Predictive Marker for Asthma?

To show that an increase in eNO, a biomarker of airway inflammation, is a risk factor expected from passage of recurrent wheezing in infancy towards childhood asthma at pre-school age (age 4 to 7 years old). Secondary objectives: - To assemble an international cohort of patients selected from homogeneous criteria established by a panel of experts. - To allow a homogeneous collection of retrospective and prospective data on childhood BD in real-time thanks to the creation of an on-line database. - To support genetic studies and conduct a parallel collection of DNA.