Comparison of Anthropometry and Body Composition Using Air Displacement Plethysmography in Term Small for Gestational Age and Appropriate for Gestational Age Neonates.

BACKGROUND

Small for gestational age (SGA) neonates are prone to growth deficits in early life, which may be associated with later life metabolic abnormalities.

OBJECTIVES

To compare anthropometry and body composition using air-displacement plethysmography (ADP) in term SGA and appropriate for gestational age (AGA) neonates, and assess if sexual dimorphism existed in estimates of body composition.

STUDY

DESIGN

Cross-sectional analytical study.

PARTICIPANTS

413 term neonates (91 SGA and 322 AGA) at birth (≤7days).

METHODS

Neonatal anthropometry and body composition were measured using ADP. Length corrected fat mass index (FMI) and fat free mass index (FFMI) were calculated.

OUTCOME: Anthropometry and body composition estimates of SGA and AGA neonates, segregated by sex.

RESULTS

The mean (SD) birth weight of SGA and AGA neonates was 2.5 (0.2) kg and 3.1 (0.3) kg, respectively. SGA neonates had significantly lower % body fat (BF) (2.0%), fat mass (94.4 g), fat free mass (FFM) (349.7 g), FMI (0.34 kg/m2), and FFMI (0.76 kg/m2), but higher %FFM (2.0%) compared to AGA neonates (P<0.001). Males had significantly higher %FFM [91.2 (3.1) vs 90.2 (3.5); P=0.001], FFM [2604 (280) vs 2442 (233) g; P<0.001], and FFMI [11.1 (0.8) vs 10.8 (0.8) kg/m2; P=0.005], but lower % BF [8.8 (3.1) vs 9.8 (3.5); P=0.001] and FMI [1.1(0.4) vs 1.2 (0.5) kg/m2; P=0.008], compared to females.

CONCLUSIONS

Accurate estimates of body composition in neonates at birth suggest significantly lower body fat and fat free mass in SGA compared to AGA, with sexual dimorphism.