In this study, a cohort of newborn presenting TTN will be followed, in order to evaluate, at initial admission, pulmonary maturation (with fetal lung maturity test and the stable microbubble test) and to seek for PPHN (echochardiography). Therapeutic management will be done according to standard care and classification of the neonate will be performed according to their clinical evolution: group 1 (uncomplicated TTN) and group 2 (complicated TTN).