Body composition and energy metabolism in pregnancy

Good performance of bioimpedance in early pregnancy to predict preeclampsia

INTRODUCTION

Preeclampsia (PE) affects 2-8% of pregnancies and is one of the main causes of maternal morbidity and mortality worldwide. Early identification of pregnant women at higher risk for PE would allow the use of interventions to reduce adverse maternal and perinatal outcomes.

OBJECTIVE

To assess the ability of bioelectrical impedance analysis (BIA) in pregnancy to predict the development of PE.

METHODS

This prospective cohort involved healthy nulliparas who underwent BIA at 17-20 weekś gestation and were followed until delivery. We used univariate and multivariate logistic regression to assess the ability of BIA measures to predict the occurrence of PE. We used an adjusted regression model to estimate the probability of developing PE, the Hosmer-Lemeshow test to assess the adequacy of the final model, and ROC curves to assess the sensitivity and specificity of different BIA measures in the prediction of PE.

RESULTS

Twelve (6.1%) of the 196 participants developed PE. In the final multivariate model, the following BIA measures were associated with the occurrence of PE: extracellular water/intracellular water ≤ 0.618, skeletal muscle mass ≥ 25 Kg, and body fat percentage ≥ 44%. The combination of these three measures had a predictive accuracy of 83.7%, a sensitivity of 83.3%, a specificity of 83.7%, and a negative predictive value of 98.7% for PE.

CONCLUSION

BIA done on nulliparous women at 17-20 weekś gestation has a good accuracy and high negative predictive value for the risk of developing PE.

Energy expenditure during pregnancy: a systematic review

CONTEXT

Contrary to nutritional guidelines, accumulating evidence shows that pregnant women's energy intakes remain stable throughout trimesters. Although pregnant women may eat below their needs or underreport their energy intakes, it is also relevant to question how energy requirements - estimated through measurements of energy expenditure (EE) - change throughout pregnancy.

OBJECTIVE

This review examined prospective studies that measured EE during pregnancy, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

PubMed/MEDLINE, Web of Science, Embase, and CINAHL databases were searched to identify relevant publications up to November 14, 2019.

STUDY SELECTION

All studies that measured EE prospectively and objectively during pregnancy were included in this systematic review. Two authors independently screened 4852 references. A total of 32 studies were included in the final analysis.

DATA EXTRACTION

One author extracted data and assessed the risk of bias and a second author did so for a random sample of studies (n = 7; 22%).

DATA ANALYSIS

Increases in resting EE ranged from 0.5% to 18.3% (8-239 kcal), from 3.0% to 24.1% (45-327 kcal), and from 6.4% to 29.6% (93-416 kcal) between early and mid-, mid- and late, and early and late pregnancy, respectively. Increases in total EE ranged from 4.0% to 17.7% (84-363 kcal), from 0.2% to 30.2% (5-694 kcal), and from 7.9% to 33.2% (179-682 kcal) between early and mid-, mid- and late, and early and late pregnancy, respectively. Participants were mainly of normal weight, although many studies did not report important covariates such as prepregnancy body mass index and gestational weight gain adequacy.

CONCLUSIONS

Additional high-quality longitudinal studies (ie, with multiple objective measurements of EE in all periods of pregnancy while considering important confounding variables, like gestational weight gain) are required.

Body composition helps: Differences in energy expenditure between pregnant and nonpregnant females

OBJECTIVES

Human pregnancy is associated with important physiological changes that usually increase energetic requirements. However, great variability exists in the costs and mechanisms required to bear pregnancy. Since body mass (BM) and composition are modified during gestation, it is of great interest to compare the influence of BM on energy expenditure (EE) in pregnant and nonpregnant females.

METHODS

BM, body composition, and EE of 77 volunteers (35 pregnant and 42 nonpregnant females) were measured. The pregnant volunteers completed two measurement rounds at 28 and 32 gestation weeks. Differences on the measured parameters were sought, and comparison of regression lines was computed to test how BM affected the EE of the volunteers.

RESULTS

BM and body composition parameters are significantly higher in pregnant females, but EE is not statistically different. Pregnant females have a larger percentage of fat mass, but lower percentage of fat-free mass (FFM). The EE per kg of FFM is similar in both groups. Comparison of regression lines shows that pregnancy does not change the relationship between BM and EE, but for similar BM pregnant females expend less energy than nonpregnant females.

CONCLUSIONS

We propose that their larger percentage of passive body tissues is the reason why pregnant females expend less energy than nonpregnant females of similar BM, without changing the scaling of EE on BM. Thus, pregnancy could not be as energetically constraining as usually assumed, with important consequences for human reproductive ecology.

Reproducibility of Bioelectrical Impedance Analysis in Pregnancy and the Association of Body Composition with the Risk of Gestational Diabetes: A Substudy of MUMS Cohort

Introduction

Bioelectrical impedance analysis (BIA) is a rapid and noninvasive method of body composition analysis; however, reproducibility between BIA instruments in pregnancy is uncertain. Adverse maternal body composition has been linked to pregnancy complications including gestational diabetes mellitus (GDM). This study aimed to evaluate the reproducibility of three BIA instruments in pregnancy and analyse the relationship between the body composition and the GDM risk.

Methods

A prospective cohort (n = 117) of women with singleton pregnancies participating in the Microbiome Understanding in Maternity Study (MUMS) at St. George Hospital, Sydney, Australia. Anthropometric measurements and BIA body composition were measured at ≤13 weeks (T1), 20-24 weeks (T2), and 32-36 weeks (T3) of gestation. Body fat percentage (BFP), total body water (TBW), and impedance were estimated by three BIA instruments: Bodystat 1500, RJL Quantum III, and Tanita BC-587. GDM status was recorded after 75 g oral glucose tolerance test was performed at 28 weeks or earlier. Agreement between BIA instruments was assessed using Bland-Altman analysis. Logistic regression modelling explored associations of BFP with GDM.

Results

Method comparison reproducibility between Bodystat and RJL was stronger than between Bodystat and Tanita for both BFP and TBW% at all three time points. RJL overestimated BFP on average by 3.3% (p < 0.001), with limits of agreement within ±5% for all trimesters. Average BFP was not significantly different between Tanita and Bodystat although limits of agreement exceeded ±5%. GDM diagnosis was independently associated with increased BFP in T1 (adjusted OR 1.117 per 1% increase; 95% CI 1.020-1.224; p=0.017) and in T2 (adjusted OR 1.113 per 1% increase; 95% CI 1.010-1.226; p=0.031) and with Asian ethnicity in all models (OR 7.4-8.1).

Conclusion

Reproducibility amongst instruments was moderate; therefore, interchangeability between instruments, particularly for research purposes, cannot be assumed. In this cohort, GDM risk was modestly associated with increasing BFP and strongly associated with Asian ethnicity.

Alterations in energy homeostasis to favour adipose tissue gain: A longitudinal study in healthy pregnant women

BACKGROUND

Pregnancy is associated with an increase in body fat; however, excessive gestational weight gain predisposes to significant maternal and neonatal morbidity and mortality. It remains unclear whether alterations in energy homeostasis have a major influence on fat storage.

AIMS

To evaluate longitudinal changes in body composition and energy metabolism in healthy pregnant women.

MATERIALS AND METHODS

Body composition, energy expenditure and energy intake were measured longitudinally in 26 women with singleton pregnancies at 12-14 weeks, 24-26 weeks and 34-36 weeks of gestation. Fat mass (FM) and lean body mass (LBM) were measured using bio-impedance analysis, total energy expenditure (TEE) using the Sensewear Armband and energy intake through a 3-day food recall diary.

RESULTS

Throughout pregnancy, all women remained healthy. Body weight increased by 10.8 ± 3.9 kg, from 67.3 ± 14.1 kg to 78.1 ± 13.8 kg from the first to the third trimester (P < 0.001). Body fat percentage increased by 4.5 ± 4.2% (P < 0.001). LBM also increased throughout pregnancy, by 3.9 ± 2.4 kg (P < 0.001). TEE increased significantly from the first to the third trimesters (9514 kJ/day to 10 263 kJ/day; P < 0.05). In contrast, energy expenditure due to physical activity, energy intake and macronutrient intake did not change significantly throughout pregnancy.

CONCLUSION

Healthy women increase FM during pregnancy despite slight increases in TEE and no change in energy intake. This suggests that energy storage efficiency improves during pregnancy, which may be related to alterations in gut microbiota and activation of anabolic pathways during pregnancy. Clarifying factors leading to this more efficient fat and energy storing state, and the role of the pregnancy-related changes in gut microbiota, may be important for managing gestational weight gain.

[Basal metabolism during pregnancy: a systematic review]

Gestational energy expenditure (EE) is the basis for nutritional counseling and body weight control. The objective of this study was to systematically review the behavior of the basal metabolic rate (BMR), the major component of EE, during non gemelar pregnancy of healthy women. Based on the inclusion criteria, 37 articles were identified (24 cohort and 13 cross-sectional studies). Increases in BMR (between 8% and 35%) were observed in most cohort studies and it was related to the duration of follow-up and nutritional status. In the cross-sectionals, the increase in BMR varied from 8% to 28% close to delivery in comparison with the first trimester or post-partum. Lack of information on maternal age, loss of follow-up and short duration of follow-up during the pregnancy were serious limitations in the identified studies. In conclusion, BMR increases during pregnancy, and the increase is more intense after the second trimester. The most reliable data come from the few cohort studies that initiated before pregnancy.

The importance of visceral fat mass in obese pregnant women and relation with pregnancy outcomes

BACKGROUND

Maternal obesity is a well established risk factor for gestational diabetes but it is not known if the pattern of maternal fat distribution predicts adverse pregnancy outcomes.

METHODS

Body composition was assessed by bioimpedance using Inbody 720® in 302 consecutive obese pregnant women attending a weight management clinic. The relation of visceral fat mass and total percentage body fat with the development of gestational diabetes and perinatal outcomes was evaluated.

RESULTS

Women developing gestational diabetes (Group 1; n = 72) were older, had higher body mass indices and greater central obesity (waist:hip ratio, visceral fat mass) compared with those remaining normoglycaemic. Visceral fat mass, but not percentage body fat, correlated with fasting glucose in all patients (r = 0.2, p < 0.001) and particularly those in Group 1 (r = 0.35, p = 0.002). Visceral fat mass, but not percentage body fat, also correlated strongly with glycaemia, particularly in Group 1 (r = 0.47, p < 0.0001). Visceral fat mass also showed a weak but significant correlation with baby weight (r = 0.17, p = 0.01).

DISCUSSION

Central obesity, as assessed by early pregnancy waist:hip ratio and particularly by visceral fat mass, is a predictor of gestational diabetes in addition to classical risk factors and may help identify those obese patients at increased risk of complications.

Systematic review and meta-analysis of energy and macronutrient intakes during pregnancy in developed countries

Research reporting diet during pregnancy in nationally representative samples is limited. This review summarizes the dietary intakes of pregnant women in developed countries and compares them with national recommendations. A systematic search without date limits was conducted. All studies reporting the macronutrient intakes of pregnant women were considered, irrespective of design. Two authors independently identified the studies to be included and assessed the methodological quality. Nutritional adequacy was summarized, with confounding factors considered. Meta-analysis data are reported for developed countries collectively, by geographical region, and by dietary methodology. Energy and macronutrient intakes of pregnant women do not match national recommendations. Energy and fiber intakes were consistently below recommendations, while total fat and saturated fat intakes were generally above recommendations and carbohydrate and polyunsaturated fat intakes were below to borderline low compared with recommendations. A mismatch between dietary practices and macronutrient recommendations in pregnant women is widespread and not well quantified. The implications of these practices are unknown until further research compares maternal diet with short-term and long-term maternal and offspring health outcomes.

Determination of Maternal Body Composition in Pregnancy and Its Relevance to Perinatal Outcomes

Three models and 10 specific methods for determining maternal body composition are discussed and their perinatal relevance reviewed. English language publications (1950 to January 2004) were searched electronically and by hand. Search terms included "body composition," "human," " pregnancy," "obesity," "adiposity," "regional," "2-, 3-, 4-component," "truncal," "peripheral," "central," "visceral" along with specific techniques and outcomes listed subsequently. Three models of body composition are described: 2-component being fat and fat-free mass; 3-component being fat, water, and protein; and 4-component being fat, water, protein, and osseous mineral. Ten techniques of body composition assessment are described: 1) anthropometric techniques including skinfold thicknesses and waist-hip ratio; 2) total body water (isotopically labeled); 3) hydrodensitometry (underwater weighing); 4) air-displacement plethysmography; 5) bio-impedance analysis (BIA); 6) total body potassium (TBK); 7) dual-energy x-ray absorptiometry (DEXA); 8) computed tomography (CT); 9) magnetic resonance imaging (MRI); and 10) ultrasound (USS). Most methods estimate total adiposity. Regional fat distribution-central (truncal) compared with peripheral (limb) or visceral compared with subcutaneous-is important because of regional variation in adipocyte metabolism. Skinfolds, DEXA, CT, MRI, or USS can distinguish central from peripheral fat. CT, MRI, or USS can further subdivide central fat into visceral and subcutaneous. Perinatal outcomes examined in relation to body composition include pregnancy duration, birth weight, congenital anomalies, gestational diabetes, gestational hypertension, and the fetal origins of adult disease. A few studies suggest that central compared with peripheral fat correlates better with birth weight, gestational carbohydrate intolerance, and hypertension. Means of accurately assessing maternal body composition remain cumbersome and impractical, but may more accurately predict perinatal outcomes than traditional assessments such as maternal weight.

Body composition and energy metabolism in normotensive and hypertensive pregnancy

OBJECTIVE

To determine whether the insulin resistance syndrome and altered body composition are features of hypertensive pregnancy.

DESIGN

Women were recruited in the third trimester of pregnancy from the antenatal clinic, day assessment unit, and maternity ward of St George Hospital, Sydney.

POPULATION

Women with pre-eclampsia (n = 12), gestational hypertension (n = 12), essential hypertension in pregnancy (n = 11), and normotensive pregnancy (n = 10).

METHODS

Energy metabolism was assessed by indirect calorimetry to measure basal metabolic rate and diet-induced thermogenesis. Body composition was measured as lean body mass, total body water and fat mass by bio-electrical impedance. Blood was collected for measurement of glucose, insulin and lipid profiles. Insulin resistance was indirectly assessed by the insulin and glucose concentrations and diet-induced thermogenesis.

RESULTS

Women with essential hypertension and gestational hypertension were heavier than women with normotensive pregnancies both pre-pregnancy and in the third trimester, whereas women with pre-eclampsia were similar to those with normotensive pregnancy. Women with essential hypertension were otherwise similar to normotensive pregnancy but women with gestational hypertension had a reduced diet-induced thermogenesis and almost double insulin levels. Women with pre-eclampsia had a similar body composition and insulin levels but reduced basal metabolic rate, diet-induced thermogenesis and glucose levels compared with normotensive pregnancy.

CONCLUSIONS

Women who develop gestational hypertension, but not pre-eclampsia, are more likely to be overweight. Women with essential hypertension are similar to women with normotensive pregnancy throughout pregnancy. Both gestational hypertension and pre-eclampsia appear to be associated with some degree of insulin resistance, greater than that occurring in normal pregnancy.