Premature infants born at 34 and 35 weeks differ in respiratory issues and length of stay due to feeding difficulties

Late preterm infants, born between 34 and 36 weeks of gestation, generally have a better clinical prognosis than those born before 33 weeks. However, detailed differences within the late preterm group have been underexplored. Therefore, this study compared the clinical outcomes of infants born at 34 and 35 weeks of gestation.

Hospital records between April 2020 and March 2024 were retrospectively analyzed, excluding cases with complications. Statistical comparisons were performed using Fisher's χ² test, Mann-Whitney U test, and simple linear regression.

Infants born at 34 weeks had lower appearance, pulse, grimace, activity, and respiration (Apgar) scores at 1 and 5 min, with a significant decrease in respiratory scores at 5 min (1-point score: 60.00% vs. 18.18%, p = 0.0041). They were also significantly more likely to require respiratory assistance at birth without specific respiratory intervention (p < 0.0001). Although birth weight showed no significant difference, 34-week-old infants had a longer duration of intravenous therapy, took longer to establish autonomous feeding, and had an extended hospital stay (median: 17 days vs. 10 days, p = 0.0017). Prolonged stays were not correlated with the duration of oxygen use or weight but were more strongly associated with feeding difficulties in 34-week-olds (r = 0.9187, p < 0.0001).

A 1-week gestational age difference in late preterm infants represents a significant clinical distinction. Infants at 34 weeks had prolonged hospital stays driven by feeding difficulties, not respiratory morbidity, challenging current uniform management approaches.