Background: Patent ductus arteriosus (PDA) causing significant left to right shunt can increase key morbidities in preterm infants. Yet, treatment does not improve outcomes and spontaneous closure is the natural course of PDA. The Impact of PDA on 23–26-week gestation infants is uncertain. Selective treatment of such infants would likely balance outcomes.Objective: To test the hypothesis that treatment of PDA in high-risk VLBW infants [birth weight ≤800 g or gestation