Bronchopulmonary dysplasia (BPD) is a serious lung condition that affects premature newborns. The condition involves abnormal development of lung tissue and is characterized by inflammation and scarring in the lungs. Treatment with inhaled nitric oxide (iNO) may reduce the incidence of BPD and another commonly associated condition called pulmonary hypertension, which is high blood pressure in the vessels carrying blood to the lungs.. This study will determine if early treatment with low-dose iNO reduces the incidence of BPD, pulmonary hypertension, and death in premature newborns.