AbstractIntroductionPerinatal management of extremely preterm births in Sweden has changed toward active care from 22–23 gestational weeks during the last decades. However, considerable regional differences exist. This study evaluates how one of the largest perinatal university centers has adapted to a more active care between 2004–2007 and 2012–2016 and if this has influenced infant survival.Material and methodsIn this historical cohort study, women admitted with at least one live fetus and delivered at 22–25 gestational weeks (stillbirths included) at Karolinska University Hospital Solna during April 1, 2004–March 31, 2007, and January 1, 2012–December 31, 2016, were compared regarding rates of obstetric and neonatal interventions, and infant mortality and morbidity. Maternal, pregnancy and infant data from 2004–2007 were obtained from the Extreme Preterm Infants in Sweden Study while data from 2012–2016 were extracted from medical journals and quality registers. The same definitions of interventions and diagnoses were used for both study periods.ResultsA total of 106 women with 118 infants during 2004–2007 and 213 women with 240 infants during 2012–2016 were included. Increases between the study periods were seen regarding cesarean delivery (overall rate 14% [17/118] during 2004–2007 vs. 45% [109/240] during 2012–2016), attendance of a neonatologist at birth (62% [73/118] vs. 85% [205/240]) and surfactant treatment at birth in liveborn infants (60% [45/75] vs. 74% [157/211]). Antepartum stillbirth rate decreased (13% [15/118] vs. 5% [12/240]) and the proportion of live births increased (80% [94/118] vs. 88% [211/240]) while 1‐year survival (64% [60/94] vs. 67% [142/211]) and 1‐year survival without major neonatal morbidity (21% [20/94] vs. 21% [44/211]) among liveborn infants did not change between the study periods. At 22 gestational weeks, interventions rates were still low during 2012–2016, most obvious regarding antenatal steroid treatment (23%), attendance of a neonatologist (51%), and intubation at birth (24%).ConclusionsBoth obstetric and neonatal interventions at births below 26 gestational weeks increased between 2004–2007 and 2012–2016 in this single center study; however, at 22 gestational weeks they were still at a low level during 2012–2016. Despite more infants being born alive, 1‐year survival did not increase between the study periods.