The study was a subproject within a Specialized Center of Research (SCOR) in Lung Biology and Diseases in Infants and Children. The clinical interventions studied had significance for respiratory distress syndrome of the newborn and for bronchopulmonary dysplasia, which is the chronic lung disorder of fibrosis, alveolar loss and reactive airway disease that often follows pulmonary disease requiring treatment with oxygen and mechanical ventilation in the newborn period.