Energy expenditure in the fetus and neonate: sources of variability.

The paper discusses fetal and neonatal energy expenditure. The extent of the variation in fetal energy expenditure is unknown, but calculations are presented to show that an average value may be around 18 kcal/kg X d, with the oxidative cost of growth being about 13% of the total. In the neonatal period there is apparently a large variation in total daily energy expenditure, perhaps as great as 70%. This is accounted for partly by methodological difficulties, but also by genetic variation in resting metabolism, and by variation in activity, nutritional state, growth rate and body composition. Data are presented from the literature to give some guidance as to the variability of energy expenditure at different weights and postnatal ages.