Timing of PDA Closure and Respiratory Outcome in Premature Infants

The investigators propose the present study with the following aims: * to determine whether early patent ductus arteriosus (PDA) treatment with ibuprofen treatment at the onset of clinical symptoms is superior to late ibuprofen treatment only when symptoms of a hemodynamically significant PDA are present in the evolution of bronchopulmonary dysplasia (BPD) defined as duration of supplemental oxygen exposure during the first 28 days * to determine whether early PDA treatment with ibuprofen will be superior to late treatment with ibuprofen in efficacy of PDA closure, need for rescue therapy, need for PDA ligation and incidence of major complications of prematurity. Hypothesis: Early pharmacologic closure of PDA with ibuprofen will improve respiratory course and reduce BPD as reflected by a reduction in duration of supplemental oxygen during the first 28 days of age vs. late pharmacologic treatment with ibuprofen. Outcome variables: The primary outcome of this study is the number of days spent on supplemental oxygen by each infant during the first 28 days. Other outcomes to be determined between groups include: * Mortality * Other respiratory variables: total days on supplemental oxygen, days on mechanical ventilation, oxygen dependence at 36 weeks post menstrual age, age at final extubation. * Other respiratory complications: pneumothorax, pulmonary interstitial emphysema, need for high frequency ventilation, pulmonary hypertension * Efficacy of PDA closure: number of courses of medication required, need for ligation * Other neonatal complications: intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), retinopathy of prematurity (ROP), necrotizing enterocolitis (NEC), intestinal perforation, sepsis, renal dysfunction (oliguria, elevated creatinine) * Time to achieving full enteral feedings, time to regain birth weight, weight at discharge. * Length of hospital stay

Study terminated when intravenous (IV) ibuprofen withdrawn for both clinical and research use.