Definition of Premature Birth A premature birth is defined as babies born alive before 37 weeks of pregnancy are completed. There are sub-categories of preterm birth, based on gestational age: Extremely preterm (<28 weeks) Very preterm (28 to <32 weeks) Moderate to late preterm (32 to <37 weeks).   Small for gestational age (SGA): Babies … Continue reading Definition of Premature Birth