Metabolic rate analysis of healthy preterm and full-term infants during the first weeks of life.
BACKGROUND
Longitudinal data on resting energy expenditure (REE) in extremely immature infants and full-term neonates are scarce but are necessary to understand the energy requirements in neonatal nutrition during the first weeks of life.


OBJECTIVE
The aim of the present study was to measure REE and its main components longitudinally during the first weeks of life to quantify their significant determinants.


METHODS
REE was investigated longitudinally over a period of 6 wk in healthy, stable, and growing preterm infants and over 5 wk in full-term neonates by means of indirect calorimetry.


RESULTS
A total of 197 infants, including 183 premature infants and 14 full-term neonates, were recruited for the study. REE values increased in all gestational age groups from the first week to 5-6 wk of postnatal age, with the most pronounced increase in the smallest infants (+140%) and the smallest increase in the full-term neonates (+47%). Univariate calculations showed that for each postnatal week, REE increased by 6.93-9.64 kcal x kg(-1) x d(-1) with each additional kcal administered, for an average increase of 0.701 kcal, and increased by 1.78 kcal for each 1 g gain in weight. Postnatal age was the strongest predictor to influence REE (r(2) = 0.727, P < 0.0001).


CONCLUSIONS
This study provides comprehensive data on longitudinally determined REE values of healthy premature and full-term infants. Results may serve as a basis for comparative studies that address various disease states as well as different nutritional protocols.
Bauer
Jacqueline
J
Department of Pediatrics and Medical Informatics, University Children's Hospital of Muenster, University of Muenster, Muenster, Germany. jacqueline.bauer@ukmuenster.de
Werner
Claudius
C
Gerss
Joachim
J
D002149:Energy Intake; D004734:Energy Metabolism; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D016014:Linear Models; D008137:Longitudinal Studies; D012146:Rest; D015430:Weight Gain