Change in body composition of premature infants from parenteral nutrition discontinuation to term equivalent age.

Aim: To compare body composition (BC) of premature infants at parenteral nutrition (PN) suspension and at term equivalent age (TEA).

Methods: Body weight, fat mass (FM), fat free mass (FFM) and FM as % of body weight were measured in infants born at <32 gestational weeks by air-displacement plethysmography at PN suspension and at TEA in a tertiary level hospital. Z-scores were calculated for BC and anthropometric measurements. Nutritional and clinical data were obtained during hospital stay. BC, weight and length were measured at birth in a sample of infants born at term for comparison.

Results: Thirty premature infants with birth weight of 1198 ± 270 g and gestational age of 29.8 ± 1.8 weeks were included. At PN suspension, at 32.6 ± 1.6 postconceptional weeks, FFM z-score was similar to FFM z-score measured at TEA, at 39.8 ± 0.7 postconceptional weeks (-1.43 ± 1.27 vs -1.78 ± 1.64, p = 0.26), while FM z-score and %FM z-score at PN suspension were lower than those measured at TEA (FM z-score: 0.23 ± 0.62 versus 2.04 ± 1.00, p < 0.0001 and %FM z-score: 0.66 ± 0.76 versus 2.08 ± 1.07, p < 0.0001). At TEA, weight and length of premature infants were similar to those of term-born infants (3130 ± 340 g vs 3350 ± 340 g; 49.2 ± 2.4 cm vs 50.2 ± 2.5 cm, respectively), but %FM was higher (21.3 ± 4.2% vs 9.2 ± 4.4%, p < 0.001); higher exclusive enteral caloric and protein intakes were associated with a decrease in FM z-scores from PN suspension to TEA.

Conclusion: In our sample of premature infants, fat free mass z-score was similar, while fat mass and % fat mass z-scores increased substantially from parenteral nutrition suspension to term-equivalent age. Nutritional intakes during exclusive enteral nutrition did not seem to contribute to such increase.