Rysavy MA, Horbar JD, Bell EF, et al. - Researchers performed a prognostic study including 3 observational cohorts from January 1, 2006, to December 31, 2016, at 19 US centers in the NRN (derivation cohort) and 637 US centers in Vermont Oxford Network (VON) (validation cohorts) to modernize and confirm the NRN extremely preterm birth outcome model for most extremely preterm infants in the United States. They recruited actively treated infants born at 22 weeks’ 0 days’ to 25 weeks’ 6 days’ gestation and weighing 401 to 1000 g, including 4176 in the NRN for 2006 to 2012, 45 179 in VON for 2006 to 2012, and 25 969 in VON for 2013 to 2016. It was noted that survival was 63% vs 62% among 3702 infants in the era of the original model (47% female; mean [SD] gestational age, 24.2 [0.8] weeks) among 4176 actively treated infants in the NRN cohort (48% female; mean [SD] gestational age, 24.2 [0.8] weeks). An updated model utilizing well-known factors to prognosticate survival for extremely preterm infants showed moderately well when used to large US cohorts. The model requires periodic updating because survival rates change over time. The hospital of birth contributed substantially with result prediction.