Evidence-based recommendations for energy intake in pregnant women with obesity

Abstract

Background: In women with obesity, excess gestational weight gain (≥270 g/week) occurs in two out of three pregnancies and contributes to metabolic impairments in both mother and baby. To improve obstetrical care, objectively assessed information on energy balance is urgently needed. The objective of this study was to characterize determinants of gestational weight gain in women with obesity.

Methods: This was a prospective, observational study of pregnant women with obesity. The primary outcome was energy intake calculated by the energy intake-balance method. Energy expenditure was measured by doubly-labeled water and whole-room indirect calorimetry and body composition as 3-compartment model by air displacement plethysmography and isotope dilution in early (13-16 weeks) and late pregnancy (35-37 weeks).

Results: In pregnant women with obesity (n=54), recommended weight gain (n=8, 15%) during the second and third trimesters was achieved when energy intake was 125±52 kcal/d less than energy expenditure. In contrast, women with excess weight gain (67%) consumed 186±29 kcal/d more than they expended (P<0.001). Energy balance affected maternal adiposity (recommended: -2.5±0.8 kg fat mass, excess: +2.2±0.5, inadequate: -4.5±0.5, P<0.001), but not fetal growth. Weight gain was not related to demographics, activity, metabolic biomarkers, or diet quality. We estimated that energy intake requirements for recommended weight gain during the second and third trimesters were not increased as compared to energy requirements early in pregnancy (34±53 kcal/d, P=0.83).

Conclusions: We here provide the first evidence-based recommendations for energy intake in pregnant women with obesity. Contrary to current recommendations, energy intake should not exceed energy expenditure.

Funding: This study was funded by the National Institutes of Health (R01DK099175; Redman, U54GM104940 and P30DK072476; Core support).

Trial registration: clinicaltrials.gov: NCT01954342.

Keywords: Clinical practice; Metabolism; Obesity; Obstetrics/gynecology; Reproductive Biology.

Figure 1. Participant throughput.

Seventy-two women were enrolled, 60 completed the late pregnancy assessment, and 54 satisfied the criteria for inclusion in the statistical analysis.

Figure 2. Rate and composition of weight gain.

(A) Gestational weight gain is shown as grams per week for each individual participant. According to 2009 Institute of Medicine guidelines, weight gain was classified as inadequate (in gray, INA, <170 g/week, n = 10), recommended (in white, REC, ≥170 g/week and <270 g/week, n = 8), and excessive (in black, EXS, ≥270 g/week, n = 36). The highlighted box shows the weight gain recommendations. (B) Data shown represent change from early (14.9 ± 0.1 weeks) to late pregnancy (35.9 ± 0.1 weeks) and are presented for each individual and as mean ± SEM for fat-free mass, fetal size, and fat mass, as observed in kilograms. Differences among weight gain groups were tested using linear mixed effect models with group used as a covariate. ****P < 0.001 of the post-hoc comparison between groups of the linear mixed model.

Figure 3. Energy intake, energy expenditure and energy balance.

(A) Energy intake (energy intake-balance method) and energy expenditure (doubly labeled water method) are presented for each individual and as mean ± SEM for 3 groups of women classified according to gestational weight gain as inadequate (in gray, INA, <170 g/week, n = 10), recommended (in white, REC, ≥170 g/week and <270 g/week, n = 8), and excessive (in black, EXS, ≥270 g/week, n = 36) by the 2009 Institute of Medicine guidelines. (B) Individual and mean ± SEM energy balance are presented as the difference in intake and expenditure for the 3 categories of gestational weight gain. Differences among weight gain groups were tested using linear mixed effect models with group used as a covariate. ****P < 0.001 of the post-hoc comparison between groups of the linear mixed model.

Figure 4. Change in energy intake estimates for gestational weight gain.

Association between gestational weight gain and change in energy intake (Change EI), calculated as calculated energy intake during pregnancy minus measured baseline total daily energy expenditure for each individual in the present study (A, n = 54), and for intervention groups in lifestyle intervention studies for pregnant women with obesity (B, by first author). The association is defined by measured data in this study and defined as Change EI [kcal/d] = 1.178 ± 0.108*GWG [g/week] –225 ± 46; R² = 0.70, in which Change EI is change in energy intake relative to early pregnancy total daily energy expenditure and GWG is gestational weight gain during the second and third trimesters. The regression line is presented with 95% confidence intervals. REC, recommended gestational weight gain (170–270 g/week).