Extrauterine growth restriction: Definitions and predictability of outcomes in a cohort of very low birth weight infants or preterm neonates

Extrauterine Growth Restriction (EUGR) refers to inadequate growth during hospitalization. Current definitions for EUGR are varied and can be classified as cross-sectional (weight at a given t-time <10th centile) or longitudinal (weight loss between birth and a given t-time >1SD). Different t-times are also considered in literature, such as 36 weeks of gestational age (GA) or age at discharge. The aim of this study is to investigate whether EUGR could predict the auxological outcome at 24–30 months, and to evaluate the agreement between cross-sectional and longitudinal definitions. In total, 1589 infants with GA <30 weeks or birthweight ≤ 1500 g and without major congenital anomalies were included in this study. Cross-sectional and longitudinal EUGR were calculated at 36 and 40 weeks of GA, at discharge, and at 28 days. The concordance between the two definitions was estimated by Kappa coefficient. At 24–30 months, 803 infants were measured again. The agreement between the two definitions of EUGR was low. Both EUGR and not-EUGR groups were at lower centiles for weight, but at higher centiles for head circumference at 24–30 months than at birth. Longitudinal EUGR was associated with a poorer growth outcome for weight and height circumference than cross-sectional EUGR. No differences were observed for length. An agreed definition of EUGR is highly desirable in clinical practice to assess medical and nutritional interventions in preterm neonates. Based on the results of this study, we recommend the use of the longitudinal evaluation, that proved to better predict the auxological long-term outcome with respect to the cross-sectional one.