Is body fat percentage a better measure of undernutrition in newborns than birth weight percentiles?

BACKGROUND: Undernutrition in neonates increases the risk of serious morbidities. The objective of this study was to describe neonatal morbidity associated with low body fat percentage (BF%) and measure the number of undernourished neonates defined by BF% and compare this with birth weight percentiles (< 10th). METHODS: Eligibility included term (>= 37 wk) neonates. BF% measurements were undertaken by air displacement plethysmography. Data on neonatal outcomes were extracted from medical records and used to develop a measure of neonatal morbidity. We assessed the association between neonatal morbidity and population-based birth weight percentiles compared with the BF% measurements. RESULTS: Five hundred and eighty-one neonates were included. Low BF% was defined by 1 SD below the mean and identified in 73 per 1,000 live births. Neonatal morbidity was found in 3.4% of neonates. Birth weight percentile was associated with neonatal morbidity (odds ratio (OR): 1.03 (95% confidence interval (CI): 1.01, 1.05); P = < 0.001). BF% was associated with a higher risk of neonatal morbidity (OR: 1.30 (95% CI: 1.15, 1.47); P = < 0.001). CONCLUSION: In this population, measuring BF% is more closely associated with identification of neonates at risk of neonatal morbidity as compared with birth weight percentiles. BF% measurements could assist with identifying neonates who are appropriately grown yet undernourished and exclude small neonates not at risk.