Long-term outcomes of preterm infants in the first 6 years of life: a nationwide population-based study in Korea.

• In this nationwide cohort study, lower gestational age at birth was inversely associated with increased adverse neurodevelopmental and respiratory outcomes in the first 6 years of life. • Long-term follow-up and policy support are required for moderate-to-late preterm children who are at risk of increased adverse outcomes compared with full-term births.