Comparison of adiposity and body composition methodology in preterm and term infants

Infant prematurity is associated with acute health risks and altered fat deposition. Aberrations in fat deposition put preterm infants at a higher risk for developing conditions such as hypertension and glucose intolerance in later life. Thus, the recommended catch-up growth for preterm infants, which only examines weight gain, may have detrimental consequences for future metabolic health. Validated, low-risk methods of accurately determining body fat deposition will assist medical professionals in monitoring interventions and optimizing growth quality in preterm infants. This study compared body fat composition in infants that were born preterm (n = 28) between 32-36 weeks postmenstrual age (PMA) and born term (n = 28) between 38-41 weeks PMA at the University of Utah Hospital. Relationships between percent body fat (%BF) measured by air displacement plethysmography (ADP) and anthropometry/skinfolds were determined. Gender and ethnic distribution were similar between the preterm and term cohorts. Age adjusted body weight, length, head circumference, and body mass index were significantly lower for preterm infants (p < 0.001). Despite the smaller body size and less mature PMA at hospital discharge, preterm infants had higher %BF by ADP (p = 0.057). In addition, mid-arm circumference was a good predictor for preterm infant %BF (p < 0.001). Our results show that preterm infants develop increased body fat percentage as they approach term-corrected age compared to term infants. This result may explain the connection between a preterm birth and metabolic consequences later in life. This study provides support for the importance of monitoring body composition in preterm infants to ensure proper growth quality.