Extrauterine growth restriction in very-low-birthweight infants: prevalence and concordance according to Fenton, Olsen, and INTERGROWTH-21st growth charts in a multicenter Spanish cohort.

Multiple criteria and growth references have been proposed for extrauterine growth restriction (EUGR). We hypothesized that these may impact the diagnosis of EUGR. The objective was to evaluate the prevalence of EUGR with its different definitions and the concordance according to Fenton, Olsen, and INTERGROWTH-21st in very-low-birthweight (VLBW) infants. This is an observational, retrospective, and multicenter study including VLBW infants from the Spanish SEN1500 Network from 2011 to 2020. Patients with major congenital anomalies, embryopathies, and gestational age less than 24 weeks were excluded. EUGR prevalence was calculated at discharge with cross-sectional, longitudinal, "true" cross-sectional, and "true" longitudinal definitions. Concordance was assessed with Fleiss' kappa coefficient. 23582 VLBW infants from 77 NICUs were included. In total, 50.4% were men with a median of gestational age of 29 (4) weeks. The prevalence of EUGR (cross-sectional, longitudinal, and "true") was variable for weight, length, and head circumference. Overall, the prevalence was higher with Fenton and lower with Olsen (cross-sectional and "true" cross-sectional) and INTERGROWTH-21st (longitudinal and "true" longitudinal). Agreement among the charts by weight was good only for cross-sectional EUGR and moderate for longitudinal, "true" cross-sectional, and "true" longitudinal. Concordance was good or very good for EUGR by length and head circumference.Conclusions: The prevalence of EUGR with the most commonly used definitions was variable in the cohort. Agreement among growth charts was moderate for all the definitions of EUGR by weight except cross-sectional and good or very good for length and head circumference. The choice of reference chart can impact the establishment of the diagnosis of EUGR. What is known: • EUGR has been defined in the literature and daily practice considering weight, length and head circumference with multiple criteria (cross-sectional, longitudinal, and "true" definition) • Different growth charts have been used for EUGR diagnosis What is new: • Prevalence of EUGR is variable depending on the definition and growth chart used in our cohort of VLBW infants • For the most frequently EUGR criteria used, traditionally considering weight, concordance among Fenton, Olsen and INTERGROWTH-21st growth charts is only moderate for all the definitions of EUGR by weight except cross-sectional definition. Concordance among the charts is good or very good for the different criteria of EUGR by head circumference and length.