Nutritional Needs of Low-Birth-Weight Infants

The basal metabolic rate of low-birth-weight infants is lower than that of full-term infants during the first week of life, but it reaches and exceeds that of the full-term infant by the second week. Daily caloric requirements reach 50 to 100 kcal/kg by the end of the first week of life and usually increase to 110 to 150 kcal/kg in subsequent active growth. A partition of the daily minimum energy requirements is shown in Table 1.6 There are considerable variations from these average values, depending on both biological and environmental factors. Infants who are small for gestational age tend to have a higher basal metabolic.rate than do premature infants of the same weight.7 The degree of physical activity appears to be a characteristic of the individual infant. Environmental factors may have a greater influence than biological variation in determining the total caloric requirements. The maximal response to cold stress can increase the resting rate of heat production up to 21/2 times.6 Calories expended for specific dynamic action and for fecal losses are dependent on the composition of the milk or formula fed, as well as on individual variations in absorption of nutrients, particularly fat. In practice, caloric intakes of 110 to 150 kcal/kg/day enable most low-birth-weight infants to achieve satisfactory rates of growth. If infants fail to gain satisfactorily, a higher caloric intake may be offered.