Increased energy expenditure and fecal fat excretion do not impair weight gain in small-for-gestational-age preterm infants

In order to optimize the nutrition of high-risk premature infants beyond th e early postnatal period, a more precise knowledge of individual nutritiona l requirements is needed. We therefore studied the influence of intrauterin e growth retardation on energy expenditure and nutrient utilization determi ned by indirect calorimetry and fecal fat excretion (steatocrit) in ninetee n premature infants who were appropriate-for-gestational-agr (AGA; mean ges tational age 29.9+/-0.3 weeks, mean birth weight 1.30+/-0.05 kg) and thirte en small-for-gestational-age (SGA) premature infants [mean gestational age 32.4+/-0.5 weeks, mean birth weight 1.024+/-0.07 kg (i.e., below the 10th p ercentile)] during the first and second month of life. All infants were cli nically stable during the study period. In nine SGA infants we observed a s ignificantly higher steatocrit compared to twelve AGA infants (29+/-1 vs. 1 7+/-1% p = 0.0001), SGA infants (n = 12) also showed a slightly (albeit sta tistically not significantly) higher energy expenditure than AGA infants (n = 15) (58.7+/-1.9 vs. 53.6+/-1.5 kcal/kg per day, p = 0.054). Despite the increased fat excretion and higher energy expenditure, SGA infants gained w eight more rapidly during the study period than AGA infants (20+/-1 vs. 17/-1 g/kg per day, p = 0.026). We conclude that influences of intrauterine g rowth retardation on energy expenditure and nutrient utilization persist du ring the first weeks of extrauterine life. However, these metabolic changes do not impair the capability of SGA infants for extrauterine catch-up grow th if adequate nutrition is provided. (C) 1999 Elsevier Science Ireland Ltd . All rights reserved.