A priori defined outcome measures
| Outcome measure | Definition |
| Bronchopulmonary dysplasia | No. of neonates who require oxygen at 36 weeks of postmenstrual age |
| Mortality | Death before discharge |
| Severe intraventricular haemorrhage | No. of neonates with grades 3–4 based on the Papile criteria |
| Air leak syndromes | No. of neonates with pneumothorax or pulmonary interstitial emphysema confirmed by chest X-ray |
| Retinopathy of prematurity (any stage) | No. of neonates with any stage of retinopathy of prematurity as per the international classification of retinopathy of prematurity |
| Neurodevelopmental impairment | No. of infants with any degree of neurodevelopmental impairment as assessed by a standardised and validated assessment tool, a child developmental specialist or both, at any age reported (outcome data grouped at 12, 18 and 24 months if available) |