Nutrient intakes and growth of very low birth weight infants

Abstract

Objective: Our purpose was to determine nutrient intakes and growth of very low birth weight (VLBW) infants.

Study design: The survey consisted of infants admitted during a 9-month period to a tertiary neonatal center. Data were obtained concerning all 51 infants born weighing <1300 gm who survived beyond 21 days of age.

Methods: At weekly intervals, intakes of fluid, energy, and protein from all sources were determined and body weight was recorded.

Results: During the first 2 weeks of life, intake of energy (predominantly parenteral) averaged 75 +/- 12 kcal/kg per day and intake of protein averaged 1.9 +/- 0.5 gm/kg per day. From 15 to 35 days, intake of energy (transition from parenteral to enteral) averaged 99 +/- 12 kcal/kg per day and intake of protein averaged 2.5 gm/kg per day. During the period 36 to 56 days (early enteral) and 57 days to term (late enteral), energy intakes were 108 +/- 13 and 110 +/- 15 kcal/kg per day, respectively, and protein intakes were 2.7 +/- 0.5 and 2.7 +/- 0.5 gm/kg per day, respectively. These low intakes of energy and protein (relative to presumed requirements) were explained by low intake volumes and low protein concentrations of feedings. Weight reached birth weight by 14 days of age. Subsequently, weight gains averaged 13.0, 13.8, and 11.6 gm/kg per day, respectively, in successive periods. These gains were lower than would have occurred in utero.

Conclusion: Observed growth of VLBW infants was slow relative to in utero growth, presumably because intakes of energy and, in particular, of protein fell short of intakes needed to duplicate in utero growth. Changes in feeding practices, as well as in composition of feedings, are needed if in utero growth is to be matched.