Objective In the Netherlands, the threshold for offering active treatment for spontaneous birth was lowered from 25(+0) to 24(+0) weeks' gestation in 2010. This study aimed to evaluate the impact of guideline implementation on survival and causes and timing of death in the years following implementation. Design National cohort study, using data from the Netherlands Perinatal Registry. Patients The study population included all 3312 stillborn and live born infants with a gestational age (GA) between 24(0/7) and 26(6/7) weeks born between January 2011 and December 2017. Infants with the same GA born between January 2007 and December 2009 (N=1400) were used as the reference group. Main outcome measures Survival to discharge, as well as cause and timing of death. Results After guideline implementation, there was a significant increase in neonatal intensive care unit (NICU) admission rate for live born infants born at 24 weeks' GA (27%-69%, p Conclusions Implementation of the 2010 guideline resulted as expected in increased NICU admissions rate and postnatal survival of infants born at 24 weeks' GA. In the years after implementation, a shift in cause of death was seen from respiratory insufficiency towards necrotising enterocolitis and sepsis.