Determination of nutritional requirements in preterm infants, with special reference to 'catch-up' growth

The usual recommendation for feeding preterm infants is to provide sufficient nutrients to support rates of growth and nutrient accretion equal to intrauterine rates. However, most preterm infants don't tolerate feedings immediately and, therefore, incur significant deficits prior to achieving sufficient intake to support growth. Furthermore, unless they receive nutrient intakes in excess of those usually recommended, they will be smaller than a fetus of the same postmenstrual age at discharge and remain smaller for some time thereafter. The consequences of these early deficits are not known with certainty but there is some evidence that they should be repleted as soon as possible. This requires a redefinition of requirements to include those for both normal growth and catch-up growth. Strategies for doing so include: more aggressive early parenteral nutrition to reduce the magnitude of early losses; greater enteral intakes of protein, and, perhaps, other nutrients once enteral feedings are tolerated; and more attention to nutrition post-discharge. Of these, the latter is somewhat problematic. This is because there seems to be a finite period - perhaps as brief as a few weeks - during which response to increased nutrient intake occurs. Firm data are limited, but those available suggest that current nutritional management of preterm infants can be improved. Whether this will have long-term benefits remains to be determined.