Table 1 Definitions for patient characteristics at enrolment, data on trial interventions and co-interventions, and neonatal outcomes.

   Complete course of antenatal corticosteroids

A course of at least 2 doses started > 48 hours before delivery or completed > 24 hours before delivery

   Antenatal corticosteroids, any treatment

Any antenatal treatment with corticosteroids, regardless of the interval with delivery

   Chorioamnionitis

As defined in the trial

   Oxygenation index (OI)

OI = MAP × F_iO₂ × 100/P _aO₂ With

   MAP = mean airway pressure

   F_iO₂ = fractional inspired oxygen

   P _aO₂ = partial arterial oxygen tension

Patient-level information on trial intervention and co-interventions

   MAP at stabilization

Mean airway pressure in the first 24 hours after randomization.

   F_iO₂ at stabilization

Fractional inspired oxygen in the first 24 hours after randomization.

   Postnatal corticosteroids

Postnatal treatment with corticosteroids for the prevention or treatment of bronchopulmonary dysplasia

   Early administration of cyclo-oxygenase inhibitor

Administration of indomethacin or ibuprofen in the first 24 hours of life in order to prevent patent ductus arteriosus or intracranial haemorrhage

Neonatal outcomes

   Death

Death before discharge from neonatal intensive care unit (NICU)

   BPD at 36 weeks PMA

Oxygen therapy at the postmenstrual age of 36 weeks

   Severe adverse neurological event

Intracranial haemorrhage grade 3 or 4, and/or cystic periventricular leukomalacia

   Gross pulmonary air leak

Pneumothorax and/or pneumomediastinum and/or pneumopericardium

   PDA requiring treatment

Patent ductus arteriosus requiring treatment with non-steroidal anti-inflammatory drugs or surgery

   Any pulmonary air leak

Gross pulmonary air leak and/or pulmonary interstitial emphysema (PIE)

   Neurological disability

Motor and/or cognitive and/or auditory and/or visual impairment