Quality of growth in premature infants fed their own mothers' milk

With the renewed interest in the feeding of human milk to preterm infants, we have evaluated the partition of energy metabolism and of macronutrient utilization and accretion in growing very low birth weight infants fed their own mother's milk. Fifteen studies combining macronutrient balance, computerized continuous open-circuit indirect calorimetry, and anthropometric measurements were performed in 11 growing, very low birth weight (less than 1.300 gm) preterm infants. The mean milk intake of 172 ml/kg/day provided a gross energy intake of 111 kcal/kg/day. Energy losses in excreta were 11 kcal/kg/day, and the metabolic energy expenditure was 56 kcal/kg/day. The remainder (44 kcal/kg/day) represented the energy stored in the components of new tissue. The infants were gaining weight (15.3 g/kg/day), length (0.98 cm/wk), and head circumference (0.76 cm/wk) at rates approximating intrauterine growth rates. The metabolic energy expenditure was derived from the oxidation (mean +/- SE) of carbohydrate, 9.5 +/- 0.7 gm/kg/day; fat, 1.63 +/- 0.34 gm/kg/day; and protein, 0.68 +/- 0.07 gm/kg/day. The stored energy comprised 2.98 +/- 0.86 gm/kg/day as carbohydrate, 2.25 +/- 0.54 gm/kg/day as fat, and 1.97 +/- 0.1 gm/kg/day as protein. The accretion rates of fat and protein, as well as the composition of the weight gain (fat, 16.6 +/- 4.1%; protein, 13.4 +/- 0.5%), were similar to those reported for the fetus of comparable gestational age.