The objective of this stuyd was to determine whether preterm birth is associated with increased risk of heart failure (HF) from childhood into mid-adulthood in a large population-based cohort. This national cohort study was conducted in Sweden with data from 1973 through 2015. All singleton live births in Sweden during 1973 through 2014 were included. In this large national cohort, preterm birth was associated with increased risk of new-onset HF into adulthood. Survivors of preterm birth may need long-term clinical follow-up into adulthood for risk reduction and monitoring for HF.