Association between Enteral Protein Intake and Fat-Free Mass Accretion in Very Preterm Infants.

Introduction: For preterm infants, the first 2 weeks after birth are a time when nutrition and protein intake is variable and often falls below recommended intakes. Our objective was to investigate the relationship between protein intake, including source of protein, during the first 2 weeks after birth and fat-free mass (FFM) accretion in a group of very preterm infants.

Methods: In this observational cohort study, body composition was assessed using air displacement plethysmography in eligible infants <32 weeks gestational age at 2 weeks after birth and prior to discharge. FFM accretion was calculated as difference between the two measurements. We collected daily nutrition data for the first 2 weeks. Multivariable linear regression was used to assess the relationship between protein intake and body composition and weight gain.

Results: Seventy-eight infants were included (mean birthweight: 1,408±278 g). Mean cumulative protein intake of this cohort in the first 2 weeks was 2.4±0.8 g/kg/day of which 74±19% was enteral (1.7±0.6 g/kg/day). Enteral protein intake was associated with higher FFM while parenteral protein was associated with lower FFM. Total protein intake from both sources during the first 2 weeks after birth was positively associated with greater weight gain.

Conclusion: Enteral protein intake during the first 2 weeks after birth is associated with higher FFM and weight in preterm infants. Future interventional studies should investigate the effects of higher enteral protein intake during the first 2 weeks after birth on growth and body composition.