Can neonates born at 34 weeks be classified as late preterm?

In recent years, much attention has been given to infants born prematurely, at 34 0/7 to 36 6/7 weeks of gestation (WG), which have been classified as 'late preterm'. Neonates from that subgroup are less physiologically and metabolically mature than term infants. The aim of the study was to determine whether infants born at 34WG can be classified as 'late preterm' or 'preterm' newborns.

A total of 141 newborns were included in the study: 25 born ≤ 33WG, 53 late-preterm newborns, and 63 term infants. Cord-blood neutrophil gelatinase-associated lipocalin (NGAL) and creatinine concentrations were measured in all newborns. Also, the incidence of clinical complications in the early adaptive period during hospitalization was evaluated.

Higher NGAL concentration was noted among preterm newborns as compared to late-preterm neonates (p < 0.05), and term newborns (p < 0.05), especially in children born at 34WG as compared to 35WG (p < 0.001). However, no differences in NGAL concentration were found between neonates born at 35WG and 36WG, as well as children born at 36WG and term infants. A relationship between umbilical NGAL levels and gestational age was observed. Additionally, a statistically significant difference was found in the incidence of respiratory distress syndrome (p < 0.05) and infections (p < 0.05) among neonates born at 34WG as compared to 35WG.

Late preterm neonates should be defined as 'preterm' between 35 0/7 and 36 6/7 WG. Infants born at 34WG should be included in the preterm group.