Late preterm delivery, defined as birth between 34 0/7 to 36 6/7 weeks’ gestation, has increased at a rate higher than that of all preterm birth for the past 20 years. It has contributed to the shift in the average gestational age at birth from 40 weeks to 39 weeks, and it is driving the increase in prematurity. Each state has seen an increase in late preterm birth, and the increasing incidence has been noted in both singleton and multiple pregnancies.

The morbidity associated with late preterm birth has been the focus of recent literature, and the importance of these findings must be underscored. Late preterm birth is associated with increased respiratory morbidities, including respiratory distress syndrome, transient tachypnea of the newborn, and the need for ventilatory support. It has also been associated with intraventricular hemorrhage, necrotizing enterocolitis, sepsis, hyperbilirubinemia, and feeding difficulties. Unfortunately, mortality is also increased in this group. Late preterm infants are at a 3- to 6-fold increased risk of death than their term counterparts. The morbidity and mortality associated with late preterm birth makes reduction of this phenomenon a priority.

The primary strategy for decreasing the rate of late preterm birth must revolve around understanding the indications for these deliveries. Many of the hypertensive disorders of pregnancy, excluding severe preeclampsia, are delivered in the late preterm period without evidence to support this practice. Other soft indications for delivery include oligohydramnios, repeat cesarean, and dichorionic twin gestation. Data are desperately needed to support the practice of early delivery in these groups of patients because neonatal morbidity and mortality associated with late preterm delivery have been established.