Early-onset hypoglycemia in late preterm infants: Small-for-gestational-age as an independent risk factor

BACKGROUND: Late preterm infants (34-36 weeks' gestation) are frequently perceived as clinically stable despite physiological immaturity that predisposes them to hypoglycemia. Evidence focused specifically on this population remains limited. This study aimed to determine the incidence, risk factors, and timing of hypoglycemia in late preterm infants. METHODS: We retrospectively analyzed 584 late preterm infants admitted between 2021 and 2024. Maternal and neonatal variables, including birth weight classification and timing of glucose measurements, were evaluated. Hypoglycemia was defined as blood glucose <45 mg/dL within the first 48 h after birth. Independent risk factors were identified using multivariable logistic regression. RESULTS: Among 584 late preterm infants, hypoglycemia occurred in 134 (22.9%). Incidence differed significantly by birth weight classification (p = 0.004). Small for gestational age (SGA) status was the strongest independent predictor (adjusted odds ratio 2.44, 95% confidence interval 1.22-4.98, p = 0.011). Most hypoglycemic episodes developed early, with the majority occurring within 6 h after birth, particularly among SGA infants. CONCLUSION: Hypoglycemia is common and occurs predominantly during the early postnatal period in late preterm infants, especially those born SGA. These findings support early and targeted glucose surveillance to facilitate timely detection and management.