Growth Monitoring in Preterm Neonates: A Narrative Review of Fenton and INTERGROWTH-21st

Preterm birth remains a major global health concern, particularly in low- and middle-income countries, where nearly 15 million babies are born preterm each year. Monitoring postnatal growth in these infants is critical, as early identification of growth faltering or extrauterine growth restriction (EUGR) influences clinical management, nutritional strategies, and long-term neurodevelopmental outcomes. Over the years, several growth references have been developed, with the Fenton 2013 and INTERGROWTH-21 st (2015) charts being the most widely used. This narrative review synthesises evidence on their methodology, clinical applications, and implications for neonatal care. The Fenton 2013 charts, derived from meta-analysis of international birth size data, align preterm growth with intrauterine expectations and WHO child growth standards at 50 weeks postmenstrual age. While widely adopted, they often classify a higher proportion of infants as EUGR. In contrast, the INTERGROWTH-21 st standards were constructed from longitudinal postnatal data of stable preterm infants under optimal care conditions across diverse populations, overlapping seamlessly with WHO standards at 64 weeks. These charts reflect realistic early postnatal growth, including physiological weight loss, thereby reducing overclassification of growth failure. Comparative studies highlight significant discrepancies in growth classification, with Fenton identifying up to threefold more EUGR cases than INTERGROWTH-21 st . This divergence has major implications for feeding strategies, discharge readiness, and long-term labelling. Ultimately, no single chart is universally superior; the choice should be tailored to clinical context, infant characteristics, and monitoring goals. Awareness of each chart’s conceptual foundation, strengths, and limitations is essential to guide evidence-based neonatal growth monitoring