Background Extrauterine growth restriction (EUGR) is common among very low birth weight (VLBW) infants and associated with poor neurodevelopmental outcomes. There are two types of EUGR definitions (cross-sectional and longitudinal) and many growth charts for monitoring postnatal growth. Aims of our study were 1) to compare the rate of small for gestational rate (SGA) and EUGR in a population of VLBW infants, both according to different growth charts (Fenton, INeS charts and Intergrowth-21) and different definitions; 2) to identify risk factors for EUGR. Methods This is a single centre retrospective observational study, including all VLBW infants born between January 2009 and December 2018. Anthropometric measures were obtained at birth and at discharge and presented as z-scores according to three growth charts (Fenton, INeS charts, Intergrowth-21). Maternal, clinical and nutritional data were retrieved from clinical records. Results 228 VLBW were included. Percentage of SGA did not change significantly according to the three different growth charts (Fenton 22.4%, INeS charts 22.8%, Intergrowth 28.2%, p 0.27). Prevalence of EUGR was significantly higher when INeS and Fenton charts were used, compared to Intergrowth charts regardless of EUGR-definition (cross sectional-EUGR: Fenton 33.5%, INeS charts 40.9%, Intergrowth-21 23.8%, p 0.001; longitudinal-EUGR (loss of 1SDS): Fenton 15%, INeS charts 20.4%, Intergrowth 4%, p <0.001). In our population a longer time to reach 100 ml/kg/day of enteral feeding increased of 18% the risk of longitudinal EUGR. Late onset sepsis and retinopathy of prematurity were associated with an increased risk of longitudinal EUGR, although not significantly, while having a preeclamptic mother was associated with a reduced risk. Conclusions We confirmed a wide variability of EUGR rates when using different charts and definitions, highlighting that Intergrowth-21 charts identify less EUGR when compared to INeS and Fenton charts. Standardized criteria for defining EUGR are warranted in order to facilitate comparisons between studies and to improve the nutritional management of VLBW infants.

Background Extrauterine growth restriction (EUGR) is common among very low birth weight (VLBW) infants and associated with poor neurodevelopmental outcomes. Prevalence of EUGR is a basic indicator of ‘nutritional care’ and an important health outcome measure. There are two types of EUGR definitions (cross-sectional and longitudinal) and many growth charts for monitoring postnatal growth. Aims of our study were 1) to compare the rate of small for gestational rate (SGA) and EUGR in a population of VLBW infants, both according to different growth charts (Fenton, INeS charts and Intergrowth-21) and according to different definitions; 2) to identify risk factors for EUGR. Methods this is a single centre retrospective observational study, including all VLBW infants born between 1st of January 2009 and 31st of December 2018. Anthropometric measures were obtained at birth and at discharge and presented as z-scores according to three growth charts (Fenton, INeS charts, Intergrowth-21). Maternal, clinical and nutritional data were retrieved from clinical records. Results 228 VLBW were included. Percentage of SGA did not change significantly according to the three different growth charts (Fenton 22.4%, INeS charts 22.8%, Intergrowth 28.2%, p 0.27). Prevalence of EUGR was significatively higher when INeS and Fenton charts were used, compared to Intergrowth charts regardless of EUGR-definition (cross sectional-EUGR: Fenton 33.5%, INeS charts 40.9%, Intergrowth-21 23.8%, p 0.001; longitudinal-EUGR (loss of 1SDS): Fenton 15%, INeS charts 20.4%, Intergrowth 4%, p < 0.001). In our population late-onset-sepsis increased the risk of longitudinal EUGR (OR: 2.69, 95%CI: 0.79–9.17), similarly as a longer time to reach 100 ml/kg of feeds (OR: 1.12, 95%CI: 0.97–1.29). On the contrary, preeclampsia was a protective factor for longitudinal EUGR. Conclusions We confirmed a wide variability of EUGR rates when using different charts and definitions, highlighting that Intergrowth-21 charts identify less EUGR when compared to INeS and Fenton charts. Standardized criteria for defining EUGR are warranted in order to facilitate comparisons between studies and to improve the nutritional management of VLBW infants.