Postnatal malnutrition and growth retardation: An inevitable consequence of current recommendations in preterm infants?

Background. Nutrient intakes meeting recommended dietary intakes (RDIs) take time to establish and once established are rarely maintained throughout hospital stay in preterm infants. A nutrient deficit, therefore, accrues. RDI are based on needs for maintenance and growth, with no provision to replace this deficit. We, therefore, hypothesized that postnatal malnutrition and growth retardation were inevitable in infants fed current RDI. Methodology. Dietary intakes were prospectively collected, by a single observer (N.P.), on a daily basis in a group of preterm infants (n = 105; birth weight less than or equal to 1750 g; gestational age less than or equal to 34 weeks) admitted to neonatal intensive care unit over a 6-month period. Actual was subtracted from recommended energy (120 kcal/kg/day) and protein (3 g/kg/day) intakes and nutritional deficits calculated. Infants were weighed on admission and throughout hospital stay. The data were analyzed using a combination of repeated measures analysis of variance and stepwise regression analysis. Results. Nutrient intakes meeting current RDIs were rarely achieved during early life. By the end of the first week, cumulative energy and protein deficits were 406 +/- 92 and 335 +/- 86 kcal/kg and 14 +/- 3 and 12 +/- 4 g/kg in infants less than or equal to 30 and those at greater than or equal to 31 weeks. By the end of the fifth week, cumulative energy and protein deficits were 813 +/- 542 and 382 +/- 263 kcal/kg and 23 +/- 12 and 13 +/- 15 g/kg and the z scores were -1.14 +/- .6 and -.82 +/- .5 for infants at less than or equal to 30 and greater than or equal to 31 weeks. Stepwise regression analysis indicated that variation in dietary intake accounted for 45% of the variation in changes in z score. Conclusions. Preterm infants inevitably accumulate a significant nutrient deficit in the first few weeks of life that will not be replaced when current RDIs are fed. This deficit can be directly related to subsequent postnatal growth retardation.