Prepregnancy body mass index and resting metabolic rate during pregnancy.
OBJECTIVE
The resting metabolic rate (RMR) varies among pregnant women. The factors responsible for this variability are unknown. This study aimed to assess the influence of the prepregnancy body mass index (BMI) on the RMR during late pregnancy.


METHODS
RMR, height, weight, and total (TEE) and activity (AEE) energy expenditures were measured in 46 healthy women aged 31 ± 5 years (mean ± SD) with low (<19.8), normal (19.8-26.0), and high (>26.0) prepregnancy BMI at 38.2 ± 1.5 weeks of gestation (t(gest)) and 40 ± 7 weeks postpartum (t(post)) (n = 27).


RESULTS
The mean t(gest) RMR for the low-, normal-, and high-BMI groups was 1,373, 1,807, and 2,191 kcal/day, respectively (p = 0.001). The overall mean t(gest) RMR was 316 ± 183 kcal/day (21%), higher than the overall mean t(post) value and this difference was correlated with gestational weight gain (r = 0.78, p < 0.001). The scaled metabolic rate by allometry (RMR/kilograms⁰·⁷³) was similar in the low-, normal-, and high-BMI groups, respectively (p = 0.45). Changes in t(gest) TEE closely paralleled changes in t(gest) RMR (r = 0.84, p < 0.001). AEE was similar among the BMI groups.


CONCLUSIONS
The RMR is significantly increased in the third trimester of pregnancy. The absolute gestational RMR is higher in women with high prepregnancy BMI due to increased body weight. The scaled metabolic rate (RMR/kilograms⁰·⁷³) is similar among the BMI groups of pregnant women.
Institute of Movement Sciences and Sports Medicine, University of Geneva, Switzerland.
Katarina
K
Melzer
Yves
Y
Schutz
Nina
N
Soehnchen
Veronique
V
Othenin Girard
Begona
B
Martinez de Tejada
Claude
C
Pichard
Olivier
O
Irion
Michel
M
Boulvain
Bengt
B
Kayser
D000328:Adult; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D011247:Pregnancy / Q000378:metabolism*; D015430:Weight Gain / Q000502:physiology