Advances in perinatal medicine have increased survival after preterm birth. What used to be a late miscarriage 50 years ago is now a developmental starting point for a whole new generation of children. The improvement is illustrated by almost universal survival (>97%) among the 383 061 preterm births that occurred in the US in 2019, translating into an estimated 6.5 million childhood survivors (age 0-18 years) of preterm birth. Consequently, the number of individuals born preterm who reach adulthood also is increasing.