Comparison of INTERGROWTH-21 and Fenton growth standards to assess size at birth and extrauterine growth in very preterm infants

This study aimed to compare the recently published prescriptive INTERGROWTH-21st standards with commonly used intrauterine based Fenton growth standards in terms of birth size classification and extrauterine growth restriction (EUGR) incidence in a sample of very preterm infants.The anthropometric measures of preterm infants born before 32 weeks of gestation at the Dokuz Eylul University Hospital during the period from January 2012 to February 2016 were obtained at birth, at the 36th gestational weeks or at the time of discharge. Birth and growth data were presented as percentiles according to the two reference standards.A total of 248 infants with mean gestational age of 29.1 ± 2.1 weeks were included. The small for gestational age (SGA) rate was significantly higher (12 versus 15%, p = .004) and the EUGR rate was significantly lower (40.2 versus 31.5%, p < .001) with the INTERGROWTH-21st charts compared with the Fentons'. Twenty-four per cent of the infants who were accepted as SGA according to the INTERGROWTH-21st standards were appropriate for gestational age (AGA) according to the Fenton preterm growth charts. However, these newly identified SGA infants according to the Intergrowth-21st standards did not have increased risks of early morbidities. Furthermore, 77% of the cases who had EUGR due to the Fenton standards were categorized as EUGR when evaluated using the INTERGROWTH-21st standards.Results indicated that almost one out of every five cases assessed as EUGR according to Fenton standards was within the normal interval according to Intergrowth standards. On the contrary, one out of every four cases assessed as SGA according to the INTERGROWTH-21st standards was within the normal interval according to Fentons'. These differences observed with INTERGROWTH-21st standards may affect in-hospital and postdischarge nutrition plan of these vulnerable infants. However, new standards are needed to be evaluated against currently used ones before they are implemented and further studies should be conducted to evaluate the functional impact of these differences on long-term outcomes including neurologic and cardio-metabolic morbidities.