New evidence-based recommendations for calorie intake in pregnant women with obesity

Researchers have provided, for the first time, evidence-based recommendations for energy intake (caloric intake) in pregnant women with obesity, making this a pioneering study in its field that can potentially help improve obstetrical care.

Excess gestational weight gain occurs in two- thirds of pregnancies and can lead to metabolic impairments in the mother and increased risk for obesity in the child. There have been several trials to evaluate the effectiveness of lifestyle interventions for pregnant women with overweight/ obesity, but only half have resulted in substantially reduced weight gain during pregnancy. Moreover, current recommendations for energy intake during pregnancy have been based only on studies in women without obesity or have been based on subjective, self-reported assessments, which are prone to recall bias. To enhance the understanding of caloric needs during pregnancy and characterize factors leading to excess gestational weight gain in women with obesity, researchers analyzed energy intake and energy expenditure (calories burned) in 54 pregnant women with obesity during the second and third trimesters using technologies and methods for rigorous, objective measurement. Applying the 2009 Institute of Medicine guidelines for gestational weight gain, 8 women from the study group gained the recommended amount of weight during the study period (approximately 4.5 kg or 9.9 lbs.) while 36 women gained an excess amount of weight (approximately 10.3 kg or 22.7 lbs.); 10 women experienced inadequate weight gain. The investigators determined that differences in weight gain were not related to differences in physical activity, physiological factors such as hormone activity, or factors such as diet quality. To understand other aspects of pregnancy-related weight gain, the researchers measured amounts of body fat in the women, as well as amounts of fat-free body tissues and fluid and calculated their energy expenditure. The women who gained the recommended amount of weight had gained that weight in fluid and fat-free body mass (including the fetus and tissues such as the placenta), while actually losing a small amount of body fat. In those who gained excess weight, the extra weight was from increased fat tissue. The researchers’ findings suggest that pregnant women with obesity should not consume extra calories during the second and third trimesters and that the energy needs of the fetus are met by mobilizing maternal fat mass to achieve healthy delivery of the infant. Importantly, these findings challenge the current recommendations for women with obesity, which advise consuming an additional 200-300 calories/day after the first trimester.

This study is unique in its use of objective methods to assess energy requirements in pregnant women with obesity and it has the potential to improve obstetrical patient care for better maternal and infant outcomes. However, it is limited by its small sample size, and evaluation of the longer-term effects on the children’s development will be important. Future research could lead to the implementation of new, evidence-based recommendations for calorie intake in pregnant women with obesity.