title: Body Composition within the First 3 Months: Optimized Correction for Length and Correlation with BMI at 2 Years.
abstract: OBJECTIVE
  Although early infant growth has implications for future health, body composition reference data in infancy are limited. The aim of this study was to describe reference data for fat mass (FM) and fat-free mass (FFM) corrected for length (L) within the first 3 months and to evaluate if these measures predict the body mass index (BMI) at 2 years.
  
  
  METHODS
  Term infants had air displacement plethysmography performed at birth (n = 1,063) and approximately 2 months later (n = 922, between 49 and 86 days). Age- and sex-specific reference data were generated for FM, FFM, FM/L3and FFM/L2and compared with BMI at 2 years.
  
  
  RESULTS
  FM/L3and FFM/L2were the optimal indices independent of length. In the first 3 months, mean FM/L3increased (males, from 2.7 to 5.9 kg/m3; females, from 3.2 to 6.1 kg/m3), whereas FFM/L2remained relatively stable (males, from 11.8 to 12.7 kg/m2; females, from 12.8 to 12.1 kg/m2). The odds of a BMI Z-score ≥2 at 2 years increased with increasing FM (OR 2.7, 95% CI 1.97-3.7) and weight (OR 2.27, 95% CI 1.64-3.13) Z-scores at 2 months.
  
  
  CONCLUSIONS
  FM/L3and FFM/L2provide length-independent measures of FM and FFM in infancy. During the first 3 months, there is an increase in FM/L3, but not in FFM/L2. The weight Z-score at 2 months is as good at predicting BMI at 2 years as body composition parameters. © 2016 S. Karger AG, Basel.
authors: Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, Philadelphia, Pa., USA.
authors: Colin P
authors: CP
authors: Hawkes
authors: Babette S
authors: BS
authors: Zemel
authors: Mairead
authors: M
authors: Kiely
authors: Alan D
authors: AD
authors: Irvine
authors: Louise C
authors: LC
authors: Kenny
authors: Jonathan
authors: J
authors: O'B Hourihane
authors: Deirdre M
authors: DM
authors: Murray
mesh_terms: D050218:Body Fat Distribution; D001827:Body Height / Q000502:physiology*; D015992:Body Mass Index; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male