Background: Weight/length (W/L) indices are poor surrogates for adiposity in preterm infants born appropriate for gestational age (AGA) at birth, but whether the association subsequently improves is unknown. Objective: To determine if W/L indices accurately reflect adiposity in premature infants born AGA in later infancy. Methods: Associations between W/L indices and fat mass, fat mass index and percent body fat (%BF) obtained via air displacement plethysmography (ADP) were examined in 260 preterm infants (majority born AGA) at 28 to 63 weeks' postmenstrual age (PMA). Accuracy of W/L indices as indicators of adiposity was assessed by proportion of variance explained (R2) and root mean square error from linear regression of adiposity on W/L indices and proportion of infants misclassified by W/L indices. Accuracy was further compared in term vs preterm infants at term-equivalent age. The impact of early vs late preterm status on associations between W/L indices and %BF was also examined. Results: BMI and W/L were most strongly associated with %BF but yielded poorly fitting models (maximum R2 = 0.35; 53% misclassification). A significant interaction of W/L indices and early vs late preterm status on %BF revealed that estimation of %BF differs by status. Accuracy of W/L indices was worse in preterm infants at term-equivalent age. Conclusions: W/L indices were not good indicators of adiposity in preterm infants from 28 to 63 weeks' PMA (born AGA) with all categories of W/L indices combined. Future research should examine whether results are similar in preterm infants born with disproportionate W/L or who experience disproportionate growth postnatally.
Bibliographical noteFunding Information:
Funding for individual studies from which data were collected for this study provided by Center for Neurobehavioral Development, Gerber Foundation, Healthy Foods for Healthy Lives Institute, March of Dimes, and the University of Minnesota Foundation (Amplatz Scholar Award). Emily Nagel was supported by the National Institutes of Health (NIH) T32 (DK083250). This content is solely the responsibility of the authors and does not necessarily represent the official views of the NIDDK or the National Institutes of Health.
© 2020 World Obesity Federation
- body composition
- premature infant
PubMed: MeSH publication types
- Journal Article