Study of the Effect of Hydrocortisone Administered for the Prevention of Pulmonary Bronchodysplasia (PREMILOC Trial) on the Determinants of Systemic Blood Pressure in Children (PREMILOCAP)

Completion of the physical activity and quality of life questionnaire (PedSQL adapted to the age of the child), measurement of weight and height; Measurement of VOP (Pulse wave velocity), AI (increase index) and ECG (electro cardiogram) collection at rest lying down; Stimulation test by slow breathing at 6 cycles/min for three minutes; Continuation of the measurements in a standing position for 5 minutes; Installation of blood pressure holter (MAPA) which will be kept for 24 hours and then returned by post.