Increased Survival Concomitant with Unchanged Morbidity and Cognitive Disability among Infants Born at the Limit of Viability before 24 Gestational Weeks in 2009-2019

The aim was to determine risk factors among mothers and outcomes for their children born at the limit of viability in 2009-2019, before and after the introduction of extended interventionist guidelines. A retrospective cohort study of births at 22 + 0-23 + 6 gestational weeks in a Swedish Region in 2009-2015 (n = 119), as compared to 2016-2019 (n = 86) after the introduction of new national interventionist guidelines. Infant mortality, morbidity, and cognitive functions at 2 years corrected age according to the Bayley-III Screening Test were monitored. Maternal risk factors for extreme preterm birth were identified. The intrauterine fetal death rates were comparable. Among births at 22 weeks, the neonatal mortality tended to decrease (96 vs. 76% of live births ( = 0.05)), and the 2-year survival tended to increase (4 vs. 24% ( = 0.05)). Among births at 23 weeks, the neonatal mortality decreased (56 vs. 27% of live births ( = 0.01)), and the 2-year survival increased (42 vs. 64% ( = 0.03)). Somatic morbidity and cognitive disability at 2 years corrected age were unchanged. We identified maternal risk factors that emphasize the need for standardized follow-up and counseling for women at increased risk of preterm birth at the limit of viability. The increased infant survival concomitant with unchanged morbidity and cognitive disability highlight the importance of ethical considerations regarding interventionist approaches at threatening preterm birth before 24 weeks.