Biochemical and anthropometric assessment of nutritional status at discharge in very-low-birth-weight infants: a retrospective cohort study

OBJECTIVES: To evaluate nutritional status at discharge in VLBW infants using biochemical and composite nutritional indices, and to examine their relationship with extrauterine growth restriction (EUGR; also termed "growth faltering" in more recent literature). METHODS: This retrospective cohort study included 124 very low birth weight infants (≤32 weeks, ≤1,500 g) admitted to a tertiary NICU (2021-2025). Anthropometric, nutritional, and biochemical parameters were recorded from birth to discharge. Four composite biochemical deficiency outcomes were constructed: protein (CPDO), nutritional (CNDO), mineral-protein (CMPDO), and protein-nitrogen (CPNDO). Multivariable Firth logistic regression and ROC analyses were performed. EUGR was defined cross-sectionally (discharge weight <10th percentile) and longitudinally (weight-for-age Z-score decline >1). RESULTS: EUGR occurred in 43.5 % (cross-sectional) and 38.7 % (longitudinal) of infants. Hypouremia (18.0 %) and hypocreatininemia (12.0 %) were the most frequent abnormalities. Composite outcomes were associated with lower gestational age and small-for-gestational-age status. Cross-sectional EUGR was nominally associated with CNDO (aOR 3.72, p=0.023) and CMPDO (aOR 3.96, p=0.031) but not CPDO; given testing across four correlated composite outcomes without formal correction for multiple comparisons, these associations should be regarded as nominal. AUCs for the four composites ranged narrowly from 0.761 to 0.794 and were not formally compared. Anthropometric differences were not significant. CONCLUSIONS: Subclinical biochemical deficiency was common at discharge despite non-significant anthropometric differences. Composite biochemical indices showed similar, moderate discriminative performance across definitions; findings are hypothesis-generating and require external, prospective validation before any composite can be considered superior or used clinically.