Serial Assessment of Body Fat and Fat-Free Mass Accretion in Very Preterm Infants: A Randomized Trial

Abstract

Abstract Objectives To incorporate assessment of body composition in the routine care of preterm infants to guide feeding practices before and after hospital discharge. Methods Very preterm infants with gestational ages between 29 and 32 weeks of gestation were included. Infants with gastrointestinal or neurologic malformations and terminal illness needing to limit or withhold support were excluded. All study participants were eligible for serial assessments of body composition between birth and 32 weeks PMA, at 36 weeks PMA or hospital discharge, and at 3 months of corrected age. Infants randomly assigned to the intervention group had the information about infant body composition available to the clinicians caring for them (including reference data). Infants randomly assigned to the control group also underwent serial assessments, but this information on infant body composition was not shown to the clinicians caring for them. The primary outcome was % body fat (%BF) estimated by air displacement plethysmography. Results Fifty very preterm infants were randomized. Mean birthweight of study participants was 1387 g +/– SD 283 and median gestational age at birth was 30 weeks (IQR: 30 – 31). Sociodemographic characteristics did not differ between groups. Mean %BF between birth and 32 weeks PMA (n = 45) was 6 +/– 4, mean %BF at 36 weeks PMA (n = 35) was 14 +/– 4, and mean %BF at 3 months of corrected age (n = 25) was 20 +/– 4. Mean differences in %BF between the intervention group and the control group were not statistically significant at 36 weeks PMA (−0.8) or 3 months corrected age (−1.2). Similarly, feeding practices during hospitalization did not differ between groups. Growth outcomes did not differ between groups. Conclusions Serial assessments of body composition at birth, 36 weeks PMA, and 3 months corrected age in very preterm infants show increased %BF in both intervention and control groups without an apparent influence of the intervention on feeding practices. While 36 weeks PMA has been a common assessment point for research purposes, body composition assessments may need to be done at earlier intervals in order to make meaningful clinical changes to the infant diet in order to affect body composition later in infancy. Funding Sources UAB OHDRC.