LAUSR

A regular subject of discussion on neonatal ward rounds is the rate of weight gain in preterm infants. This is because we believe that good nutrition is important for optimal body growth, including brain growth and development. In this issue, Andrews et al 1 demonstrate that it is possible to get close to what many consider the holy grail of preterm nutrition, which is matching the rate of fetal growth as displayed on the WHO preterm growth chart. In this article, we identify some of the difficulties with this concept and suggest priorities for research. The third trimester of pregnancy is a period of rapid growth. Normal fetal physiology is abruptly challenged at the time of preterm delivery, by the difficulty in sustaining the rate of nutrient supply, and as a result of major changes in environment including: (1) air breathing and increased tissue oxygen availability; (2) milk feeding; and (3) bacterial colonisation. The physiological alterations, including major changes in gene expression resulting from adaptation to these new conditions, mean that the use of fetal growth as a standard for preterm infants, and assumptions about weight gain as a surrogate for the quality of neonatal tissue growth need to be considered carefully. Very low birthweight preterm infants frequently develop an early fall-off in neonatal weight centile level (‘centile lag’) when assessed against a fetal growth standard and tend to occupy a lower weight centile at discharge than at birth.2 This is accompanied by a nutrient deficit when compared with the same period in fetal life.3 Much has been made of the correlation between a greater centile lag in the neonatal period and neurodevelopmental impairment4 despite the likelihood of residual confounding factors and the lack of data from intervention trials. This has encouraged the assumption that the greater the weight …