Registry to Evaluate INOmax in Newborn Babies With Pulmonary Hypertension

Inclusion Criteria: 1. Was either a P neonate born at least 27 weeks to less than 34 weeks of gestational age (GA) or a TNT neonate born at least 34 weeks but no more than 40 weeks of GA. 2. Was administered INOmax therapy after birth to 7 days of age via any route (invasive or noninvasive ventilation) for a minimum treatment period of at least 24 hours up to 96 ± 12 hours. The participants may receive INOmax for a longer period. 3. Had PH, as confirmed by echocardiogram or a differential saturation gradient of at least 10%. 4. Received INOmax administration as part of routine clinical practice in a Level III or higher neonatal intensive care unit in the United States. 5. Has all variables required to calculate OI or SOI (a baseline sample prior to treatment and 4 samples obtained during treatment). Exclusion Criteria: 1. Was at risk of imminent death (death expected within 24 hours). 2. Received extracorporeal membrane oxygenation (ECMO). 3. Had a life-threatening abnormality (cranial, cardiac, thoracic), chromosomal abnormality, congenital diaphragmatic hernia, congenital heart defect (other than patent ductus arteriosus or small atrial septal defect). 4. Had been resuscitated requiring chest compressions within 6 hours of receiving INOmax. 5. Had Grade IV bilateral intraventricular hemorrhage or periventricular leukomalacia. 6. Had active uncontrolled bleeding. 7. Had disseminated intravascular coagulopathy. 8. Had active seizures while receiving anticonvulsants. 9. Experienced prolonged asphyxia with evidence of severe acidosis (pH \< 7.25). 10. Received concomitant pulmonary vasodilator therapy (eg, prostacyclin or sildenafil) except when sildenafil was used to wean the participant from INOmax therapy.