The Usefulness of Birth Weight Z-Score as a Predictor of Catch Up Growth in Preterm Infants

ABSTRACT

PURPOSE: The aim of the study was to examine whether the degree of fetal smallness in small for gestational age (SGA) infants would increase the risk of catch-up-growth failure at 12 and 24 months corrected age (CA), and whether the high-calorie nutritional support would improve catch-up growth between 12 and 24 months CA. METHODS: We conducted a retrospective cohort study on 103 preterm infants born between January 2010 and December 2011. Logistic regression analysis was performed to investigate whether the birth weight z-score would be an independent risk factor for catch-up growth failure at 12 or 24 months CA. Among the 46 infants with failed catch-up growth at 12 months CA, 16 infants were provided high-calorie nutritional support, including nutritional supplements and medium chain triglyceride (MCT) oil at the pediatric gastroenterology clinic. RESULTS: Of 103 preterm infants, 34 infants (33%) were SGA and 69 infants (67%) were appropriate for gestational age (AGA). One birth weight z-score decrement increased the odds for catch-up growth failure 2.9 times at 12 months CA and 3.0 times at 24 months CA after adjustment for major neonatal morbidities. The increase in z-score between 12 and 24 months CA was significantly greater in the infants provided nutritional support than in the infants who were not provided nutritional support. CONCLUSION: The birth weight z-score can be used as a predictor of catch-up growth failure. High-calorie nutritional support may improve weight gain during the second year in preterm infants with failed catch-up growth at 12 months CA.