Comparison of macronutrient concentration of preterm human milk between two milk expression techniques and two techniques for quantitation of energy.

Generally, when newborns in intensive care units receive human milk, we do not know the quantity of nutrients in that milk because such analysis is time-consuming and expensive. In our study, however, we sought to compare fat, protein, lactose, and energy concentration of a three-times-a-day sampling with a 24-h expression and to measure the difference between the calculated energy yield from protein, fat, and carbohydrate measurements and bomb calorimetry. At 14-18 days postpartum, 20 mothers of premature infants (30-34 weeks' gestation) expressed milk three times a day: 8 a.m., 12 p.m., and 8 p.m. At these three times, each mother expressed 3-5 ml of fore-milk and 3-5 ml of hind-milk for the sampling; the result was pooled for a 24-h expression. Only fat concentration differed significantly between fore- and hind-milk samples. Protein, fat, lactose, and energy concentration did not differ significantly between the two collection methods, 24-h expression and sampling. Moreover, we found no significant difference between the calculated number for energy content and the bomb calorimetry method of energy determination. The average fore- and hind-milk samples at 12 p.m. matched the 24-h milk expression. For clinical use, a milk sample obtained around 12 p.m. can predict macronutrient concentration, therefore allowing us to calculate an infant's approximate nutrient consumption.