Postnatal growth and extrauterine growth retardation (EUGR) in extremely low gestational age newborns (ELGAN) with a 2-year follow-up

Objective: The primary objective of our study was to investigate the growth patterns of extremely low gestational age newborns (ELGAN) in the Neonatal Intensive Care Unit (NICU), assess the prevalence of Extrauterine Growth Restriction (EUGR) among them, and identify factors influencing its development. Additionally, the study aimed to evaluate the consistency between cross-sectional and longitudinal EUGR in ELGANs and assess catch-up growth at corrected 24 months. Method: Growth patterns of ELGANs and additional clinical data were retrospectively collected from January 2021 to January 2022 at a single tertiary NICU. EUGR was defined using two methods: cross-sectional EUGR and longitudinal EUGR. Infants were classified into two groups—EUGR and non-EUGR—based on whether their weight z-score was below -1.28 at the time of evaluation (either at a corrected gestational age (CGA) of 36 weeks or at discharge, whichever occurred first) or if the z-score decline (ΔZ score) exceeded 1 standard deviation (SD) between birth and the time of evaluation. According to WHO Child Growth Standards, catch-up growth was assessed at the age of two. Results: The study included 66 ELGANs. The incidence of EUGR was 51.5% (34 out of 66) based on the cross-sectional definition, increasing to 74.2% (49 out of 66) under the longitudinal definition. Using the criterion of a ΔZ weight < –1, the EUGR group took longer to achieve total enteral nutrition and required more days of total parenteral nutrition than the non-EUGR group. Additionally, the average weight growth velocity (GV) was significantly lower in the EUGR group. Late-onset sepsis (LOS), cumulative antibiotic exposure, and feeding intolerance (FI) were significantly more prevalent in the EUGR group. Among ELGANs discharged with EUGR (based on the longitudinal definition), 53% achieved catch-up growth in weight by one year of age and 77% by two years. Conclusion: The present study highlights the importance of LOS as an independent risk factor for developing EUGR and underscores the need for interventions to reduce its incidence. Additionally, enhanced enteral nutrition support and strategies to promote higher growth velocity may effectively reduce the incidence of extrauterine growth restriction in ELGANs. Approximately 25% of ELGAN infants are expected to remain underweight by the age of two years, while the majority achieve normalization of head circumference.