Postnatal Weight Increase and Growth Velocity of Preterm Very Low Birth Weight Infants: Perspectives on Absolute Velocity Charts

Abstract

Very low birth weight (VLBW) infants’ survival has greatly increased in the last few decades thanks to the improvement in obstetrical and neonatal care. These neonates represent about 1–1.5% of all liveborn infants in developed countries and they constitute the large majority of the population in neonatal intensive care units (NICUs). The correct evaluation of postnatal growth of these babies is nowadays of primary concern, although the definition of their optimal postnatal growth pattern is still controversial. It is known that VLBW infants have a specific postnatal growth pattern markedly different from that of higher birthweight full-term infants. Prospective longitudinal studies are needed to trace VLBW infants’ growth charts not only for weight but also for length and head circumference. These charts will be a useful tool to monitor postnatal growth of VLBW infants both during hospitalisation and after discharge, up to 2 or 3 years of age. A useful tool in VLBW infants growth evaluation could also be absolute velocity charts that, allowing a better and earlier identification of growth anomalies, could permit the observation of phenomena not yet visible on distance charts. An “extrauterine growth restriction” during hospitalisation is well known in VLBW infants, in particular VLBW infants with pathological conditions fail to thrive, but it is still not precisely known in which postnatal age periods and to what extent some factors act on growth pattern.