Background There is increasing evidence that intrauterine growth restricted (IUGR) fetuses alter in utero nutrient metabolism in order to survive their environment, and this fetal adaptation is associated with long term health disorders. It has been speculated that “overfeeding” a metabolism designed for a decreased nutrient intake may contribute to these health problems.
Study The goal of this study was to determine if preterm infants with definitive IUGR (BWT≤3%, progressive growth failure in utero, and abnormal Doppler umbilical blood flows) demonstrate abnormal postnatal nitrogen metabolism in the immediate postnatal period when compared to appropriately grown (AGA) infants of comparable gestational age. All infants received exclusive parenteral nutrition. IUGR infants were pair matched with AGA controls for the following parameters by order of importance to the study outcome: protein intake, gestational age, hours of age at study, energy intake. The primary outcome variable was protein balance as determined by the nitrogen balance method.
Results Data from 15 IUGR/AGA pairs are shown in the table below. Analysis is by paired t-test, though mean ± SEM data is presented; p≤0.05 considered significant.
Conclusion Although this study was not able to detect differences in estimated protein accretion rates in IUGR vs AGA preterm neonates, we speculate these differences may exist, and that future studies using different experimental strategies (e.g. using increased amino acid intakes, studying infants for a longer duration, using more sensitive protein metabolism methodology) may be able to define these differences.