Early aggressive nutrition in very preterm infants.

Despite numerous advances in the nutrition of preterm infants, the increasing survival at lower birth weights is resulting in a new frontier of extrauterine nutritional support of these vulnerable infants. The extremely low birth weight infant has endogenous energy to maintain energy balance for only 3-4 days without an exogenous energy supply. Nevertheless, many clinicians are still hesitant to introduce substrates at high rates early in life secondary to concerns of intolerance and toxicity. Current feeding practices appear to be resulting in significant postnatal growth failure in very preterm neonates. Optimizing nutritional support in these infants is critical to avoiding adverse growth and neurological outcomes. There is a need for scientifically based feeding strategies to achieve normal in utero growth rates postnatally. Important areas for research include determination of safe and efficacious upper limits of energy and amino acid intake, identification of markers for protein toxicity, better characterization of the effect of various neonatal illnesses and the neonatal stress response on nutritional metabolism, development of enteral feeding strategies that will allow for more rapid enteral feeding advance while reducing the risk of necrotizing enterocolitis, and understanding the benefits and risks of both over- and undernutrition in the extremely low birth weight infant.