A Noninvasive Approach to Body Composition in the Neonate: Dynamic Skinfold Measurements

Abstract

Extract: Midtricipital (MT) and subscapular (SS) skinfolds were measured within 24 hr of birth in 23 normally grown mature (NG-M); 23 normally grown premature (NG-P); 6 intrauterine growth-retarded mature (IGR-M); and 7 intrauterine growth-retarded premature (IGR-P) infants. A rapid initial decrease in measured skinfold thickness (SFT) occurred after application of a Harpenden caliper, but readings stabilized by 60 s (SFT60). Measurements were recorded at 15 and 60 s. The difference between 15− and 60-s readings was expressed in percentage of the 15-s reading (percentage ΔSFT). The amount of subcutaneous fat, estimated from the SFT60 measurements, was affected by duration of gestation in the NG-M and NG-P and the IGR-M and IGR-P groups. In both NG groups, good linear correlations with birth weight (r = 0.852 at MT and 0.874 at SS, P < 0.001) and with gestational age (r = 0.842 at MT and r = 0.804 at SS, p < 0.001) were evident. Values for intrauterine growth-retarded infants deviated markedly from the mean SFT60 expected for their gestational age. Percentage ΔSFT was affected by duration of maturation but not by impaired intrauterine growth. It correlated with gestational age (r = −0.777 at MT and −0.773 at SS, P < 0.001) and with maximal postnatal weight loss (r = 0.579 at MT and 0.553 at SS, P < 0.001) in all groups and with birth weight in the premature groups only (r = −0.479 at MT and −0.520 at SS, P < 0.01). The similarity of these trends with those of direct extracellular water measurements suggested that percentage ΔSFT may be an estimate of subcutaneous interstitial water. Speculation: Changes in body composition during fetal life include fat deposition in the subcutaneous and internal body stores and a decrease in the proportion of body weight occupied by water. Intrauterine growth retardation results in lower fat stores and expansion of all body water compartments. The present data suggest that skinfold thickness recorded 60 s after caliper application and the difference between the 15-and 60-s readings provide estimates of fat stores and subcutaneous interstitial water, respectively. Caliper skinfold measurements can therefore be used for noninvasive studies of perinatal body composition and nutrition.