Preterm birth, or birth before 37 weeks' gestation, is increasingly common, occurring in 8 percent of pregnancies in Canada. Preterm birth is associated with many health complications, particularly when the birth happens before 29 weeks' gestation. At this gestational age, the lungs are not fully developed and it is not uncommon for infants to have problems breathing at the time of birth. One complication that can arise is when an infant stops breathing and needs to be resuscitated. When preterm babies need to be resuscitated doctors must take special care because of the small infant size and the immaturity of the brain and lungs. Oxygen is used to resuscitate babies who need it, but unfortunately there is disagreement about the best oxygen concentration to use. Oxygen concentration is important because both too much and too little oxygen can cause brain injury. This research aims to fill this knowledge gap by participating in an international clinical trial to compare the effects of resuscitating babies less than 29 weeks' gestational age with either a low oxygen concentration or a high oxygen concentration. The oxygen concentrations have been selected using the best available knowledge. This will be a cluster randomized trial where each participating hospital will be randomized to either 30 or 60 percent oxygen for the recruitment of 30 infants, and afterwards randomized to the other group for the recruitment of another 30 infants. After the trial, the investigator will determine whether the babies resuscitated with low oxygen or those resuscitated with high oxygen have better survival and long-term health outcomes. This research fills a critical knowledge gap in the care of extremely preterm babies and will impact their survival both here in Canada and internationally.