What are the names given to babies that are born early?

Babies born early are commonly referred to as "preterm" or "premature" infants. Specifically, those born before 37 weeks of gestation are classified as preterm. The earlier they are born, the more specific terms may be used, such as "extremely preterm" for those born before 28 weeks and "very preterm" for those born between 28 and 32 weeks.