Background Resuscitation at birth with 100% oxygen is known to increase the oxidative burden with concomitant deleterious effects. Although fractions of inspired oxygen (FiO2)??88%, Apgar score at 5 min, cumulative O2 exposure, oxidative stress (as determined by glutathione synthesis and oxidative stress markers), retinopathy of prematurity, brain injury and neurodevelopmental outcome at 2 years of age. This study will provide insight into determining the appropriate initial FiO2 to start resuscitation of very preterm infants.