Development of whole body adiposity in preterm infants

The long-term effects of prematurity, early diet and catch-up growth on metabolic risk and body adiposity are of increasing interest to Neonatologists. Poor growth is known to be associated with poorer neuro-developmental outcome but concern exists that increased rates of "catch-up" (or "recovery") growth may be associated with increased adiposity and the later development of metabolic syndrome. In this manuscript we review the published data on body composition in preterm infants, and present new analyses of body adiposity in preterm infants during the 12-15 months of life, and the effect of growth rate (weight gain) on body adiposity. We conclude that although preterm infants have increased adiposity at term corrected age, they generally have lower body fat than their term peers during the rest of the 12-15 months of life. Although more rapid "catch-up" growth in preterm infants during the first year of life is associated with greater body fatness than slower rates of growth, these higher rates of growth lead to body composition more similar to that of the term-born infant, than do slower rates of growth. Although more studies are needed to determine whether these short-term increases or the longer-term decreases in adiposity modify the risk on chronic diseases such as diabetes mellitus, hypertension or other components of the metabolic syndrome, the widely held concern that preterm babies have greater adiposity than their term peers, and that this is worsened by greater amounts of catch-up growth, are not supported by the available evidence.