Effect of body weight on temperature control and energy expenditure in preterm infants

The purpose of this study was to compare resting energy expenditure (REE) in premature infants of different body weights during weaning from the incubator. We hypothesized that premature infants would respond to weaning from an incubator with an increase in REE, and that the increment would be larger in infants with lower body weights than in those with higher body weights. Stable preterm infants with body weights between 1800-2200 g were enrolled. REE was measured using indirect calorimetry at 1 hour before weaning and 3 hours after turning off the incubator. REE measurements from infants with higher body weight (2000-2200 g, Group A) were compared to those of infants with lower body weight (1800-2000 g, Group B). A total of 22 patients were studied (10 in Group A and 12 in Group B). REE increased significantly after weaning in both groups (Group A: from 62 ± 7 kcal/kg/day to 69 ± 8 kcal/kg/day, p = 0.045 and Group B: from 65 ± 5 kcal/kg/day to 70 ± 7 kcal/kg/day, p = 0.001). However, there was no significant difference in REE increments between the two groups. REE increased significantly in infants during weaning from an incubator. The increase in REE increment was similar in smaller (1800-2000 g) and larger (2000-2200 g) babies in this study. Weaning of preterm babies from an incubator may be safely started when their body weight reaches 1800 g.