Babies arriving 4 to 6 weeks early are significantly more likely to develop respiratory distress syndrome, sepsis, intraventricular hemorrhage, hypoglycemia, and jaundice requiring phototherapy
A recent retrospective study of spontaneous, low-risk, singleton, late preterm (between 34 and 37 weeks' gestation) deliveries finds that, compared with full-term infants, the babies arriving 4 to 6 weeks early were significantly more likely to develop respiratory distress syndrome (4.2% vs. 0.1%, P<.001), sepsis (0.4% vs. 0.04%, P<.001), intraventricular hemorrhage (0.2% vs. 0.02%, P<.001), hypoglycemia (6.8% vs. 0.4%, P<.001), and jaundice requiring phototherapy (18% vs. 2.5%, P<.001). The study, conducted in Israel, included almost 2,500 late preterm babies and almost 7,500 full-term controls.
The authors report that the relationship between gestational age and neonatal morbidity is of a continuous nature with a nadir at about 39 weeks' gestation. The relationship does not, as previously believed, have a term–preterm threshold, nor is it related to birthweight. They also found that among late-preterm babies, risk factors that further increase morbidity risk include cesarean delivery, male sex, and parity.
The authors concluded that given the short- and long-term neonatal morbidity, hospitalization days, and costs associated with late prematurity, practitioners may want to consider doing more to prolong pregnancy when spontaneous preterm labor occurs beyond 34 weeks' gestation.