Energy Expenditure Assessment of Preterm Infant With Very Low Birth Weight Fed With Human Milk or Preterm Formula

Post-natal growth restriction has become a problem yet to be solved and studied in most neonatal units. Newborns with very low birth weight grow at a rate lower than expected, thus culminating with delayed extra-uterine growth, be it in the term assessment, be it at the time of discharge from the hospital, and this makes the search for adequate nutrition a critical issue. Although there are intrinsic risk factors related to prematurity, the nutritional approach of the neonatal unit staff plays a decisive role on the prevalence of malnutrition.

Although the importance of appropriate nutritional management of premature infants has been clearly recognized, the necessary nutrient requirements of most nutrients have not been well established yet and these uncertainties may contribute to a limited intake of nutrients (Hay et al, 1999).

When fresh and extracted mother´s own milk, human milk has been considered the preferred feed for premature newborns, because of its digestibility, balanced chemical composition, capacity to provide immunity and prevention of future diseases (AAP, 2003). In addition, human milk has been associated to lower energy expenditure to be used in comparison with preterm formula, and this may promote the newborn's growth (Lubetzky et al, 2003). However, many of its advantages can be lost when human milk comes from a pool and is pasteurized, and its use has been associated to inadequate weight gain and a nutritional deficit during hospital stay. Thus it is sometimes necessary to use human milk with fortifier or preterm formula, to feed the preterm infant, in order to increase caloric-protein supply and weight gain. Milk formulas for premature babies have currently high caloric density and are better digested, but they do not have the capacity to provide immunity. In face of this problem, several studies are in progress to know and discuss the best nutritional approach for premature newborns during hospital stay. Among the factors that may have an impact on this approach is energy expenditure originated from the type of diet newborns have and on how its caloric constituents (macronutrients) are metabolized.

In face of the aforesaid, the following question remains: Will individually adjusting the caloric density of human and formula milk fed to newborns with very low birth weight actually have any impact on energy expenditure?

2 - OBJECTIVES