Estimation of neonatal body fat percentage predicts neonatal hypothermia better than birthweight centile

Abstract

Introduction

PEA POD™ air displacement plethysmography quickly and noninvasively estimates neonatal body fat percentage (BF%). Low PEA POD™ BF% predicts morbidity better than classification as small-for-gestational-age (SGA; <10th centile), but PEA PODs are not widely available. We examined whether skinfold measurements could effectively identify neonates at risk; comparing skinfold BF%, PEA POD™ BF% and birthweight centiles’ prediction of hypothermia – a marker of reduced in utero nutrition.

Methods

Neonates had customized birthweight centiles calculated, and BF% prospectively estimated by: (i) triceps and subscapular skinfolds using sex-specific equations; and (ii) PEA POD™. Medical record review identified hypothermic (<36.5 °C) episodes.

Results

42/149 (28%) neonates had hypothermia. Skinfold BF%, with an area under the curve (AUC) of 0.66, predicted hypothermia as well as PEA POD™ BF% (AUC = 0.62) and birthweight centile (AUC = 0.61). Birthweight <10^th centile demonstrated 11.9% sensitivity, 38.5% positive predictive value (PPV) and 92.5% specificity for hypothermia. At equal specificity, skinfold and PEA POD™ BF% more than doubled sensitivity (26.2%) and PPV increased to 57.9%.

Conclusion

Neonatal BF% performs better to predict neonatal hypothermia than birthweight centile, and may be a better measure of true fetal growth restriction. Estimation of neonatal BF% by skinfold measurements is an inexpensive alternative to PEA POD™.

Keywords:

• Air displacement plethysmography
• neonatal skinfolds
• fetal growth restriction
• neonatal morbidity
• hypothermia

Acknowledgements

The authors thank the health information services, postnatal ward, nursery, and the university research department at the Mercy Hospital for Women for their assistance in conducting this study. The authors thank the philanthropic donors to the Mercy Health Foundation for their generous support.

Disclosure statement

The authors declare they have no conflict of interests to disclose.

Author contributions

TM conceived the study. KD, ST, LH, SW and TM designed the study. SW and ST secured funding for the study. KD and SW secured ethics approvals for the study. KD, AM and TM recruited participants and performed neonatal body composition measurements. LG and TM assigned birthweight centiles for study infants. SB and TM performed the data analysis. JC provided expert pediatric advice. SB wrote the first draft of the paper and all authors provided input and approved the final manuscript.

Additional information

Funding

NHMRC Grant #1065854 to SW; Australian Government Research Training Program Scholarship to TM; Mercy Health Foundation philanthropic funding for purchase of the COSMED PEA POD™ air displacement plethysmography device. NHMRC provided salary support to ST [# 1136418]. Funding sources had no involvement in study design, collection or analysis of data, or in the writing or submission of this manuscript.