ObjectivesIt is unclear how newer methods of respiratory support for infants born extremely preterm (EP; 22–27 weeks gestation) have affected in-hospital sequelae. We aimed to determine changes in respiratory support, survival and morbidity in EP infants since the early 1990s.DesignProspective longitudinal cohort study.SettingThe State of Victoria, Australia.ParticipantsAll EP births offered intensive care in four discrete eras (1991–1992 (24 months): n=332, 1997 (12 months): n=190, 2005 (12 months): n=229, and April 2016–March 2017 (12 months): n=250).Outcome measuresConsumption of respiratory support, survival and morbidity to discharge home. Cost-effectiveness ratios describing the average additional days of respiratory support associated per additional survivor were calculated.ResultsMedian duration of any respiratory support increased from 22 days (1991–1992) to 66 days (2016–2017). The increase occurred in non-invasive respiratory support (2 days (1991–1992) to 51 days (2016–2017)), with high-flow nasal cannulae, unavailable in earlier cohorts, comprising almost one-half of the duration in 2016–2017. Survival to discharge home increased (68% (1991–1992) to 87% (2016–2017)). Cystic periventricular leukomalacia decreased (6.3% (1991–1992) to 1.2% (2016–2017)), whereas retinopathy of prematurity requiring treatment increased (4.0% (1991–1992) to 10.0% (2016–2017)). The average additional costs associated with one additional infant surviving in 2016–2017 were 200 (95% CI 150 to 297) days, 326 (183 to 1127) days and 130 (70 to 267) days compared with 1991–1992, 1997 and 2005, respectively.ConclusionsConsumption of resources for respiratory support has escalated with improved survival over time. Cystic periventricular leukomalacia reduced in incidence but retinopathy of prematurity requiring treatment increased. How these changes translate into long-term respiratory or neurological function remains to be determined.