Late preterm gestation: physiology of labor and implications for delivery.

The late preterm infant represents a significant portion of preterm deliveries. Historically, this cohort has been referred to as near-term, which may not address adequately the increased perinatal morbidity these neonates experience. The changing demographics of pregnant women also are increasing the number of inductions in this gestational age group. More women with chronic hypertension, diabetes, and other chronic medical problems are getting pregnant, and often these pregnancies may require induction during this gestational age. The increasing numbers of multi-fetal gestations also have an average gestational age at delivery in this range of 34 to 36.6 weeks. Preeclampsia is another factor that can lead to delivery and induction during this gestational age. This article discusses some of the physiologic causes behind late preterm deliveries.