Energy expenditure in the immediate postpartum period: Indirect calorimetry versus predictive equations

The aim of this study was to evaluate the resting energy expenditure (REE) of postpartum women by indirect calorimetry and to provide the most appropriate predictive equations to estimate it.

This was a cross-sectional study with 79 women in the maternity unit of a Brazilian city hospital. Information regarding age, income, gestational age, and breastfeeding was collected. Height, weight, and body composition were measured. We measured REE by indirect calorimetry and predicted REE using eight equations. Analysis of comparison, correlation, agreement, and accuracy was performed.

The median of measured REE was 1224 kcal (95% confidence interval [CI], 1157.4-1330), and the predicted REE ranged from 1213.8 (95% CI, 1207.3-1261.9) to 1553.1 kcal (95% CI, 1430.8-1488.5). No difference was found in REE between mothers who breastfed and those who did not (P = 0.994); however, there was a positive correlation with lean mass (r = 0.336; P = 0.003) and weight (r = 0.237; P = 0.036). The best predictor of REE was the Harris Benedict equation, with lower difference (P = 0.876), better median of adequacy (99.8%), and better interclass correlation coefficient (0.289). The Schofield equation was next, with greater percentage of accuracy (33.3%) and lower opposite agreement (7.6%).

All predictive equations showed low agreement and accuracy, and, in most cases, the results were overestimated. These findings indicate the need for continued studies to propose more suitable methods to determine the energy requirements for this population.