Key PointsQuestionDoes risk of bronchopulmonary dysplasia (BPD) or death modify the effect of hydrocortisone in extremely preterm infants?FindingsIn this secondary analysis of a randomized clinical trial including 799 extremely preterm infants, baseline risk for grades 2 to 3 BPD or death estimated using infants’ gestational age, birth weight, sex, respiratory support, and fraction of inspired oxygen was not associated with either benefit or harm from hydrocortisone exposure.MeaningDifferences in the association of hydrocortisone with death, BPD, or neurodevelopmental impairment were not identified when analyzed by infants’ baseline risk for BPD or death.