Upper arm anthropometry is not a valid predictor of regional body composition in preterm infants.

BACKGROUND Upper arm anthropometry has been used in the nutritional assessment of small infants, but it has not yet been validated as a predictor of regional body composition in this population. OBJECTIVE Validation of measured and derived upper arm anthropometry as a predictor of arm fat and fat-free compartments in preterm infants. METHODS Upper arm anthropometry, including the upper arm cross-sectional areas, was compared individually or in combination with other anthropometric measurements, with the cross-sectional arm areas measured by magnetic resonance imaging, in a cohort of consecutive preterm appropriate-for-gestational-age neonates, just before discharge. RESULTS Thirty infants born with (mean +/- SD) a gestational age of 30.7 +/- 1.9 weeks and birth weight of 1,380 +/- 325 g, were assessed at 35.4 +/- 1.1 weeks of corrected gestational age, weighing 1,785 +/- 93 g. None of the anthropometric measurements are reliable predictors (r(2) < 0.56) of the measurements obtained by magnetic resonance imaging, individually or in combination with other anthropometric measurements. CONCLUSION Both measured anthropometry and derived upper arm anthropometry are inaccurate predictors of regional body composition in preterm appropriate-for-gestational-age infants.