title: Gender- and gestational age-specific body fat percentage at birth.
abstract: BACKGROUND
  There is increasing evidence that in utero growth has both immediate and far-reaching influence on health. Birth weight and length are used as surrogate measures of in utero growth. However, these measures poorly reflect neonatal adiposity. Air-displacement plethysmography has been validated for the measurement of body fat in the neonatal population.
  
  
  OBJECTIVE
  The goal of this study was to show the normal reference values of percentage body fat (%BF) in infants during the first 4 days of life.
  
  
  METHODS
  As part of a large population-based birth cohort study, fat mass, fat-free mass, and %BF were measured within the first 4 days of life using air-displacement plethsymography. Infants were grouped into gestational age and gender categories.
  
  
  RESULTS
  Of the 786 enrolled infants, fat mass, fat-free mass, and %BF were measured in 743 (94.5%) infants within the first 4 days of life. %BF increased significantly with gestational age. Mean (SD) %BF at 36 to 37⁶/⁷ weeks' gestation was 8.9% (3.5%); at 38 to 39 weeks' gestation, 10.3% (4%); and at 40 to 41⁶/⁷ weeks' gestation, 11.2% (4.3%) (P < .001). Female infants had significantly increased mean (SD) %BF at 38 to 39⁶/⁷ (11.1% [3.9%] vs 9.8% [3.9%]; P = .012) and at 40 to 41⁶/⁷ (12.5% [4.4%] vs 10% [3.9%]; P < .001) weeks' gestation compared with male infants. Gender- and gestational age-specific centiles were calculated, and a normative table was generated for reference.
  
  
  CONCLUSIONS
  %BF at birth is influenced by gestational age and gender. We generated accurate %BF centiles from a large population-based cohort.
authors.affiliation: Department of Paediatrics and Child Health, University College Cork, Cork, Ireland.
authors.forename: Colin P
authors.initials: CP
authors.lastname: Hawkes
authors.forename: Jonathan O'B
authors.initials: JO
authors.lastname: Hourihane
authors.forename: Louise C
authors.initials: LC
authors.lastname: Kenny
authors.forename: Alan D
authors.initials: AD
authors.lastname: Irvine
authors.forename: Mairead
authors.initials: M
authors.lastname: Kiely
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: Murray
mesh_terms: D000273:Adipose Tissue; D050154:Adiposity; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D010991:Plethysmography; D012737:Sex Factors