The underestimation of immaturity in late preterm infants

Late preterm infants with gestational ages between 34 0/7 and 36 6/7 weeks are known to be at higher risk of mortality and morbidity than term newborns. This study aims to investigate the nature and frequency of neonatological complications in the late preterm population resulting in neonatal intensive care unit admissions as well as to draw obstetrical conclusions from the results.

Neonatological outcomes of 893 consecutively born late preterm infants were evaluated and classified by the frequency of occurrence in relation to potential maternal or fetal risk factors.

Out of 893 late preterm infants, 528 (59.1 %) required intensive neonatal care. The incidence of apnea and bradycardia, the occurrence of feeding difficulties and the requirement of continuous positive airway pressure (CPAP) were inversely proportional to gestational age (p < 0.001). Gestational diabetes of the mother was more frequently associated with hypoglycemia (p < 0.001), but showed a reduced risk of hypothermia (p < 0.001). Small for gestational age neonates had a significantly lower rate of respiratory disorders (p < 0.001), but were more often affected by feeding difficulties (p < 0.01). Normal vaginal delivery had a significant advantage with regard to the necessity of CPAP (p < 0.01) and the occurrence of feeding difficulties (p < 0.05). Infants born by cesarean section were at higher risk of hypoglycemia (p < 0.001), but at lower risk of hyperbilirubinemia (p < 0.001).

The high risk of a problematic neonatological outcome in late preterms requires fundamental reconsideration. All efforts to prolong a pregnancy should be made beyond the 34th week of gestation.