When the study was begun in 1988, infants with BPD who survived to NICU discharge required home oxygen therapy for months to years. In addition, they had a 50-69 percent chance of re-hospitalization and an 11-36 percent probability of death in the first year of life. Although improvement with age was often seen, pulmonary function abnormalities persisted into late childhood or beyond in at least 75 percent. Among other associated morbid sequelae were myocardial and pulmonary vascular dysfunction, cor pulmonale, systemic hypertension, growth failure, and neurodevelopmental abnormalities. Pathologic studies showed structural pulmonary and myocardial abnormalities in the most severely affected infants.