Body fat mass and basal metabolic rate in Dutch women before, during, and after pregnancy: a reappraisal of energy cost of pregnancy

Weight gain and body composition during pregnancy: a randomised pilot trial with probiotics and/or fish oil

We evaluated the effects of fish oil and/or probiotic supplementation in a randomised placebo-controlled intervention pilot trial on gestational weight gain (GWG) and body composition. Additionally, the influence of gestational diabetes (GDM) on GWG and body composition was assessed. We randomised 439 overweight women into intervention groups: fish oil + placebo, probiotics + placebo, fish oil + probiotics and placebo + placebo (fish oil: 1·9 g DHA and 0·22 g EPA and probiotics: Lactobacillus rhamnosus HN001 and Bifidobacterium animalis ssp. lactis 420, 1010 colony-forming units each). GDM was diagnosed with oral glucose tolerance test. Body composition was measured with air displacement plethysmography at randomisation (mean 13·9) and in late pregnancy (mean 35·2 gestational weeks). Intervention did not influence mean GWG or change in body fat mass/percentage (P > 0·17). Body composition in early pregnancy did not differ between the women who did or did not develop GDM (adjusted P > 0·23). Compared with the normoglycaemic women (n 278), women diagnosed with GDM (n 119) gained less weight (7·7 (sd 0·4) v. 9·3 (sd 0·4) kg, adjusted mean difference -1·66 (95 % CI -2·52, -0·80) and fat mass (0·4 (sd 0·4) v. 1·8 (sd 0·3) kg, adjusted mean difference -1·43 (95 % CI -2·19, -0·67) during the follow-up. In conclusion, adiposity of pregnant overweight women was not affected by supplementation with fish oil and/or probiotics, nor did it predict the development of GDM. However, adiposity was reduced in women with GDM compared with normoglycaemic women irrespective of the dietary intervention.

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 measurement by air displacement plethysmography in pregnancy: Comparison of predicted versus measured thoracic gas volume

OBJECTIVES

Body composition measurements with air displacement plethysmography (ADP) define body volume, which must be corrected for thoracic gas volume (TGV). We hypothesized that physiologic changes owing to pregnancy could affect the accuracy of predicted TGV and introduce errors into body composition measurements.

METHODS

We investigated the effect of measuring versus predicting TGV on the accuracy of body composition calculations measured with ADP in overweight and obese pregnant women. The fat and fat-free masses of 110 women were determined with ADP with predicted and measured TGV.

RESULTS

Measured TGV decreased from early to late pregnancy (P = 0.0002). Compared with measured TGV, predicted TGV was 6.3% higher during early gestation and 12.6% higher during late gestation (both P ≤ 0.001). The use of predicted instead of measured TGV in body composition calculations resulted in an overestimation of fat mass by 0.8% during the early stage, and 2.6% during the late stage of pregnancy (both P ≤ 0.001).

CONCLUSIONS

Measuring TGV increases the accuracy of body composition measurement by ADP in overweight and obese women, particularly during the late stage of pregnancy.

Dietary quality influences body composition in overweight and obese pregnant women

BACKGROUND & AIMS

Excessive adiposity and gestational weight gain (GWG) have been linked with maternal and offspring morbidity. We investigated the relation of maternal diet, physical activity and GWG on body composition in overweight and obese pregnant women.

METHODS

Fat mass (FM) and fat free mass (FFM) of 110 overweight and obese pregnant women were measured by air displacement plethysmography in early and late pregnancy (mean 13.5 and 35.3 gestational weeks). At the same time points, the quality of overall diet was assessed by validated index of diet quality (IDQ) questionnaire (score < 10/15 denotes poor dietary quality and score ≥ 10/15 denotes good dietary quality), nutrient intakes by 3-day food diaries, and physical activity by questionnaire. Weight gain between early and late pregnancy was compared to the gestational weight gain guidelines issued by Institute of Medicine.

RESULTS

Of the women, 77% gained more weight than recommended; this was related to greater dietary fat consumption (80 ± 21 g/day vs. 67 ± 11 g/day, p = 0.010) and greater increase in FM (2.7 ± 3.0 kg vs. -1.0 ± 2.4 kg, p < 0.001) compared to women with ideal GWG. Dietary protein intake (g) correlated positively with FFM at both time points (early pregnancy: r = 0.31, p < 0.002, late pregnancy: r = 0.39, p < 0.001). Women with higher dietary quality index score had more FFM, compared to women with lower dietary quality (early pregnancy FFM: 48.8 ± 5.8 kg vs. 45.8 ± 4.7 kg, p = 0.004, late pregnancy FFM: 56.1 ± 6.4 kg vs. 53.4 ± 5.6 kg, p = 0.025). No correlations were detected between total energy intake or physical activity and FM or FFM at early or late pregnancy.

CONCLUSIONS

Body composition changes from early to late pregnancy were related to the amount of weight gained and overall dietary quality during pregnancy. Higher dietary quality and protein intake were associated with greater FFM, while dietary fat intake was related to excess weight gain. Identification of these dietary determinants of body composition and weight offers new targets for dietary counseling of pregnant women and thus potential for ensuing health benefits through reduced adiposity.

Anthropometric and ultrasound measures of maternal adiposity in the first trimester of pregnancy

Aim

Estimations of central adiposity in pregnancy is a difficult undertaking due to physiological changes that occur in the body. Therefore, the value of some anthropometric measures particularly in pregnancy, such as body mass index (BMI), waist and hip measures are in doubt. The aim was to compare ultrasound (US) measured abdominal subcutaneous fat (USSFT) with other simple anthropometric methods for obesity assessment, evaluating these measures in pregnancy.

Method

Recruited from a larger study, anthropometric measurements were performed between 11-14 weeks' gestation on 575 women. Measuring height, weight, hip, waist circumference, skin-folds of the triceps, thigh and supra-iliac and USSFT. Percentage maternal fat mass was calculated using skin-fold measures. Correlations of these measures were performed to gauge relationships.

Results

The anthropometric measures demonstrated good correlation (0.54-0.93) between individual adipose measures skin-folds, waist, hip, waist to height ratio (WSR) and USSFT with BMI, percentage fat mass and weight. USSFT correlated well with all anthropometric measures (0.54-0.73) correlating best with waist, WSR, BMI and weight. Waist/hip ratio demonstrated a poor correlation with USSFT, BMI, percentage fat mass and weight (0.3-0.41). Mean anthropometric measures were stratified across BMI categories describing adiposity distribution.

Conclusion

USSFT correlates well with most anthropometric measures in early pregnancy. Limitations of the gravid uterus on waist measurements, hydration and compressibility of skin-fold measures and pregnancy influences on weight and BMI assessments could be overcome using US measures. There is a potential for post hoc evaluation using US for pregnancy complications. Maternal research could benefit from a more accurate measure of adiposity.

Prepregnancy body mass index influences lipid oxidation rate during pregnancy

INTRODUCTION

The influence of maternal body mass index (BMI) on respiratory quotient during pregnancy is not clear. We aim to evaluate longitudinal changes in energy expenditure, respiratory quotient, and substrate oxidation rates in normal and overweight women with uncomplicated pregnancies. We hypothesized that the threshold period in switching from a predominantly carbohydrate to a predominantly lipid metabolism may be different in normal and overweight women.

MATERIAL AND METHODS

Forty healthy pregnant women were recruited for a prospective cohort study. They were divided into two groups, normal and overweight (BMI <25 kg/m² or ≥25 kg/m² ). Comparisons of indirect calorimetry data were performed monthly throughout pregnancy. The relationships between energy and substrate metabolism variables and maternal BMI were also analyzed.

RESULTS

There was a significant increase in oxygen consumption (Vo₂ ), carbon dioxide production (Vco₂ ) and resting energy expenditure during pregnancy in both normal and overweight women. In the normal weight group, respiratory quotient decreased during the second trimester and increased in the last trimester. Respiratory quotient was lower in the overweight group in the second trimester and decreased in the last trimester; between-group differences being significant at 20 and 36 weeks (0.85 ± 0.06 vs. 0.81 ± 0.01, p = 0.009; 0.87 ± 0.05 vs. 0.80 ± 0.03, p = 0.01, respectively). Lipid oxidation was significantly higher in overweight women at both 20 and 36 weeks (36.8 ± 19.7% vs. 55.2 ± 5.6%, p = 0.003 and 33.6 ± 18.2% vs. 59.6 ± 12.7%, p = 0.007, for normal and overweight group, respectively).

CONCLUSION

Prepregnancy maternal BMI influences lipid oxidation rate and respiratory quotient during pregnancy.

Nutrition for Multiples

In 2012 there were 135,943 infants of multiple pregnancies born in the United States, nearly a 2-fold increase since 1980, with twins accounting for 96% of all multiple births. To date, most perinatal morbidities associated with multiple births have proven resistant to technological or pharmaceutical interventions. Maternal nutrition can have a profound effect on the course and outcome of multiple pregnancy, with the goal of achieving optimal intrauterine growth and birthweights, and minimizing prenatal and perinatal complications for the mother and her children.

Effects of an antenatal dietary intervention on maternal anthropometric measures in pregnant women with obesity

OBJECTIVE

The effect of providing antenatal dietary and lifestyle advice on secondary measures of maternal anthropometry was evaluated and their correlation with both gestational weight gain and infant birth weight was assessed.

METHODS

In a multicenter, randomized controlled trial, pregnant women with BMI of ≥25 kg/m(2) received either Lifestyle Advice or Standard Care. Maternal anthropometric outcomes included arm circumference, biceps, triceps, and subscapular skinfold thickness measurements (SFTM), percentage body fat (BF), gestational weight gain, and infant birth weight. The intention to treat principles were utilized by the analyses.

RESULTS

The measurements were obtained from 807 (74.7%) women in the Lifestyle Advice Group and 775 (72.3%) women in the Standard Care Group. There were no statistically significant differences identified between the treatment groups with regards to arm circumference, biceps, triceps, and subscapular SFTM, or percentage BF at 36-week gestation. Maternal anthropometric measurements were not significantly correlated with either gestational weight gain or infant birth weight.

CONCLUSIONS

Among pregnant women with a BMI of ≥25 kg/m(2) , maternal SFTM were not modified by an antenatal dietary and lifestyle intervention. Furthermore, maternal SFTM correlate poorly with both gestational weight gain and infant birth weight.

Factors determining insulin requirements in women with type 1 diabetes mellitus during pregnancy: a review

Most women with type 1 diabetes mellitus (T1DM) have increased insulin requirements during pregnancy. However, a minority of women have a fall in insulin requirements. When this occurs in late gestation, it often provokes concern regarding possible compromise of the feto-placental unit. In some centres, this is considered as an indication for delivery, including premature delivery. There are, however, many other factors that affect insulin requirements in pregnancy in women with type 1 diabetes mellitus and the decline in insulin requirements may represent a variant of normal pregnancy. If there is no underlying pathological process, expedited delivery in these women is not warranted and confers increased risks to the newborn. We will explore the factors affecting insulin requirements in gestation in this review. We will also discuss some novel concepts regarding beta-cell function in pregnancy.

Respiratory quotient evolution during normal pregnancy: what nutritional or clinical information can we get out of it?

Food intake increases to a varying extent during pregnancy to provide extra energy for the growing fetus. Measuring the respiratory quotient (RQ) during the course of pregnancy (by quantifying O2 consumption and CO2 production with indirect calorimetry) could be potentially useful since it gives an insight into the evolution of the proportion of carbohydrate vs. fat oxidized during pregnancy and thus allows recommendations on macronutrients for achieving a balanced (or slightly positive) substrate intake. A systematic search of the literature for papers reporting RQ changes during normal pregnancy identified 10 papers reporting original research. The existing evidence supports an increased RQ of varying magnitude in the third trimester of pregnancy, while the discrepant results reported for the first and second trimesters (i.e. no increase in RQ), explained by limited statistical power (small sample size) or fragmentary data, preclude safe conclusions about the evolution of RQ during early pregnancy. From a clinical point of view, measuring RQ during pregnancy requires not only sophisticated and costly indirect calorimeters but appears of limited value outside pure research projects, because of several confounding variables: (1) spontaneous changes in food intake and food composition during the course of pregnancy (which influence RQ); (2) inter-individual differences in weight gain and composition of tissue growth; (3) technical factors, notwithstanding the relatively small contribution of fetal metabolism per se (RQ close to 1.0) to overall metabolism of the pregnant mother.

[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.

Changes in resting and walking energy expenditure and walking speed during pregnancy in obese women

BACKGROUND

Energy-conserving processes reported in undernourished women during pregnancy are a recognized strategy for providing the energy required to support fetal development. Women who are obese before conceiving arguably have sufficient fat stores to support the energy demands of pregnancy without the need to provoke energy-conserving mechanisms.

OBJECTIVE

We tested the hypothesis that obese women would show behavioral adaptation [ie, a decrease in self-selected walking (SSW) speed] but not metabolic compensation [ie, a decrease in resting metabolic rate (RMR) or the metabolic cost of walking] during gestation.

DESIGN

RMR, SSW speed, metabolic cost of walking, and anthropometric variables were measured in 23 women aged 31 ± 4 y with a BMI (in kg/m(2)) of 33.6 ± 2.5 (mean ± SD) at ≈15 and 30 wk of gestation. RMR was also measured in 2 cohorts of nonpregnant control subjects matched for the age, weight, and height of the pregnant cohort at 15 (n = 23) and 30 (n = 23) wk.

RESULTS

Gestational weight gain varied widely (11.3 ± 5.4 kg), and 52% of the women gained more weight than is recommended. RMR increased significantly by an average of 177 ± 176 kcal/d (11 ± 12%; P < 0.0001); however, the within-group variability was large. Both the metabolic cost of walking and SSW speed decreased significantly (P < 0.01). Whereas RMR increased in >80% of the cohort, the net oxygen cost of walking decreased in the same proportion of women.

CONCLUSION

Although the increase in RMR was greater than that explained by weight gain, evidence of both behavioral and biological compensation in the metabolic cost of walking was observed in obese women during gestation. The trial is registered with the Australian Clinical Trials Registry as ACTRN012606000271505.

Weight retention within the puerperium in adolescents: a risk factor for obesity?

OBJECTIVE

The present study aimed to investigate weight retention and body composition in the postpartum period between adolescent girls and older women.

DESIGN

A prospective cohort study. Anthropometry and skinfold thickness measurements were performed at the first antenatal visit and at 6 weeks postpartum. An FFQ was administered at 6 weeks postpartum to explore the relationship between diet and postpartum weight retention.

SETTING

Clinics at the University of the West Indies, Kingston, Jamaica.

SUBJECTS

Recruitment included women aged 19 years and younger (adolescent girls) and 20 years and older (older women).

RESULTS

Three hundred and forty women were studied. Adolescent girls had significantly lower measurements compared with the older women at the first antenatal visit and at 6 weeks postpartum. Dietary intakes of energy and macronutrients were similar in both groups. Postnatal assessments showed that adolescent girls retained more weight (P = 0.003) and a greater percentage of body fat (P < 0.002) than older women. In multiple regression analyses, 0.982 kg more fat mass was retained postpartum in the adolescent group compared with the older women, while there was no significant difference in lean body mass retained between the two groups.

CONCLUSIONS

Adolescent girls retained more weight postpartum and this was predominantly fat mass as opposed to lean body mass.

Do the changes in energy balance that occur during pregnancy predispose parous women to obesity?

The aim of this review was to re-assess whether the changes in energy balance that accompany pregnancy predispose parous women to obesity. A number of cross-sectional studies have sought to answer this question by examining the relationship between parity and maternal body weight. However, these studies were unable to control for the large number of sociobehavioural confounders that might be responsible for the apparent effect of parity on body weight. Longitudinal studies that examine changes in maternal body weight before and after regnancy avoid these problems by using each mother as her own control. Nevertheless, these studies have to overcome three methodological constraints: They must obtain an accurate measure of prepregnant body weight, they must give each mother sufficient time to lose any weight retained following delivery, and they must take into account the effect of ageing on maternal weight gain during pregnancy and the follow-up period. More than 90% of the studies reviewed found body weight to be greater after pregnancy than it was before (by 0.2–10.6kg). and previous researchers who have examined the evidence for pregnancy-related weight gains suggest that body weight increases by an average of 04–4.8kg following pregnancy. However, only three of the 71 longitudinal studies examined in the present review complied with the three methodological criteria. These studies concluded that mothers gain, on average, 0.9–3.3kg more weight following pregnancy than nonpregnant controls, and that mean body weight remained 0.4–3.0kg higher, even after controlling for a number of sociobehavioural confounders. This apparently modest increase in mean maternal body weight for women having one or two children conceals the fact that some mothers experience a substantial increase in body weight and become obese following pregnancy. It remains unclear whether these increases are simply the result of changes in energy metabolism during pregnancy and lactation, or whether they are influenced by inherent changes in lifestyle that accompany pregnancy and motherhood. Understanding the relative importance of these alternatives might help to explain the aetiology of maternal obesity.

“Clover was a stout motherly mare approaching middle life, who had never quite got her figure back after her fourth foal”

George Well (1945) Animal Farm. London: Secker and Warburg.

Early treatment of the pregnant guinea pig with IGFs promotes placental transport and nutrient partitioning near term

Appropriate partitioning of nutrients between the mother and conceptus is a major determinant of pregnancy success, with placental transfer playing a key role. Insulin-like growth factors (IGFs) increase in the maternal circulation during early pregnancy and are predictive of fetal and placental growth. We have previously shown in the guinea pig that increasing maternal IGF abundance in early to midpregnancy enhances fetal growth and viability near term. We now show that this treatment promotes placental transport to the fetus, fetal substrate utilization, and nutrient partitioning near term. Pregnant guinea pigs were infused with IGF-I, IGF-II (both 1 mg.kg-1.day-1) or vehicle subcutaneously from days 20-38 of pregnancy (term=69 days). Tissue uptake and placental transfer of the nonmetabolizable radio analogs [3H]methyl-D-glucose (MG) and [14C]aminoisobutyric acid (AIB) in vivo was measured on day 62. Early pregnancy exposure to elevated maternal IGF-I increased placental MG uptake by>70% (P=0.004), whereas each IGF increased fetal plasma MG concentrations by 40-50% (P<0.012). Both IGFs increased fetal tissue MG uptake (P<0.048), whereas IGF-I also increased AIB uptake by visceral organs (P=0.046). In the mother, earlier exposure to either IGF increased AIB uptake by visceral organs (P<0.014), whereas IGF-I also enhanced uptake of AIB by muscle (P=0.044) and MG uptake by visceral organs (P=0.016) and muscle (P=0.046). In conclusion, exogenous maternal IGFs in early pregnancy sustainedly increase maternal substrate utilization, placental transport of MG to the fetus, and fetal utilization of substrates near term. This was consistent with the previously observed increase in fetal growth and survival following IGF treatment.

Validation of three predictive equations for basal metabolic rate in adults

Objective

To cross-validate three predictive set of equations for basal metabolic rate (BMR) developed by Schofield (Schofield database), Henry (Oxford database) and Cole (Oxford database) using mean values for age, weight, height and BMR of published studies.

Design

Literature review of studies published from 1985 to March 2002.

Setting

All studies selected used appropriate methods and followed conditions that met the criteria established for basal metabolism, were performed in healthy adults, and were not part of the Schofield or Oxford database.

Subjects

A total of 261 groups of men and women from 175 studies were selected and categorised in three age groups (18.5–29.9, 30.0–59.9, ≥60 years old) and three body mass index (BMI) groups (normal weight, overweight and obese).

Results

Linear regression and concordance correlation analysis showed that the three sets of equations had the same association and agreement with measured BMR, across gender, age, and BMI groups. The agreement of all equations was moderate for men and poor for women. The lowest mean squared prediction errors (MSPRs) were given by Henry equations in men and Cole equations in women. Henry and Cole equations gave lower values than Schofield equations, except for men over 60 years of age. Henry equations were the most accurate in men. None of the three equations performed consistently better in women.

Conclusion

These results support the use of Henry equations in men with a wide range of age and BMI. None of the proposed predictive equations seem to be appropriate to estimate BMR in women.

Nutrition in multiple gestations

Multiple pregnancies represent a state of magnified nutritional requirements, resulting in a greater nutrient drain on maternal resources and an accelerated depletion of nutritional reserves. Maternal weight gain to 20 weeks and between 20 and 28 weeks has the greatest effect on birthweight in twin and triplet pregnancies, particularly among underweight women. Parity, which most likely represents a higher proportion of body fat, has a positive effect on pregnancy outcome, with an average 7 to 10 days longer gestation for multiparous versus nulliparous women. In addition to being the nutrients most often lacking in a woman's diet, calcium, magnesium, and zinc have been identified as having the most potential for reducing pregnancy complications and improving outcomes.

Composition of gestational weight gain impacts maternal fat retention and infant birth weight

OBJECTIVE

The purpose of this study was to evaluate how changes in gestational weight and body composition affect infant birth weight and maternal fat retention after delivery in underweight, normal-weight and overweight women.

STUDY DESIGN

We assessed the body composition of 63 women (low body mass index, 17 women; normal body mass index, 34 women; and high body mass index, 12 women) on the basis of measurements of total body nitrogen by prompt-gamma activation analysis, total body potassium by whole body counting, and a multicomponent model based on total body water by deuterium dilution, body volume by densitometry, and bone mineral content by dual energy x-ray absorptiometry (DXA) before pregnancy, at 9, 22, and 36 weeks of gestation, and at 2, 6, and 27 weeks after delivery. Infant weight and length were recorded at birth; infant anthropometry and body composition by DXA were assessed at 2 and 27 weeks of age.

RESULTS

Gestational weight gain was correlated significantly with gains in total body water, total body potassium, protein, fat-free mass, and fat mass (P=.001-.003). Gains in total body water, total body potassium, protein and fat-free mass did not differ among body mass index groups; however, fat mass gain was higher in the high body mass index group (P=.03). Birth weight was correlated positively with gain in total body water, total body potassium, and fat-free mass (P<.01), but not fat mass. Postpartum weight and fat retention were correlated positively with gestational weight gain (P=.001) and fat mass gain (P=.001) but not with total body water, total body potassium, or fat-free mass gain.

CONCLUSION

Appropriate, but not excessive, gestational weight gain is needed to optimize infant birth weight and minimize maternal postpartum fat retention.

Nutritional assessment and support during pregnancy

This article thoroughly updates the authors' previous review of nutritional assessment and support during pregnancy. After briefly reviewing nutrient metabolism and requirements, the authors discuss the nutritional assessment of the pregnant woman and review the nutritional support principles in hyperemesis gravidarum and other conditions that can compromise the nutritional health of mother or fetus.

Energy intake and expenditure of free-living, lactating Colombian women in an urban setting

OBJECTIVES

To examine the components of energy balance during lactation in a population of economically disadvantaged women in an urban developing country setting in order to better understand the metabolic response to lactation.

DESIGN

Cross-sectional comparison of lactating (LACT) and non-pregnant non-lactating (NPNL) women. Body size and composition were assessed via anthropometry, energy intake was measured using estimated diet records and energy expenditure using indirect calorimetry and the Flex-Heart Rate method.

SETTING

Low-income neighborhoods of Cali, Colombia.

SUBJECTS

Lactating women (n=15) studied at 2.4+/-0.8, 5.5+/-0.8 and 8.9+/-1.2 months postpartum, and NPNL women (n=48) studied in three measurement rounds at 0, 3.5+/-0.6 and 7.1+/-1.0 months.

RESULTS

There were no significant differences between LACT and NPNL women in anthropometric dimensions, but LACT women showed decreases in waist-hip ratio, lean body mass and increases in mid-arm circumference and percentage body fat with time. Energy intake was higher in LACT women (P=0.04), but there were no significant between-group differences in energy expenditure variables.

CONCLUSION

This group of women met the cost of lactation principally via increased energy intake.

Body composition and energy metabolism in pregnancy

The objective of the study was to measure energy metabolism and body composition during pregnancy and postpartum, compared to non-pregnant women, using non-invasive techniques. A longitudinal study of eight normotensive pregnant women was carried out at 19 +/- 1 and 36+/-1 weeks gestation, and postpartum. A cross-sectional study was also performed comparing postpartum to 12 non-pregnant women. Indirect calorimetry was performed while fasting to measure basal metabolic rate (BMR) and postprandially to measure diet-induced thermogenesis (DIT). Body composition consists of fat mass, lean body mass (LBM), and total body water (TBW) and was measured by bio-electrical impedance. Insulin resistance was indirectly assessed by glucose and insulin concentration and DIT.

A longitudinal study of maternal anthropometric changes in normal weight, overweight and obese women during pregnancy and postpartum

Many women associate one or more of their pregnancies with the development of adult obesity. Such an association has not been fully explored. This longitudinal study examines the changes in maternal anthropometric indices during pregnancy and postpartum. Seventy-seven pregnant subjects were investigated longitudinally at about 13, 25 and 36 weeks gestation, of whom forty-seven continued taking part into the postpartum period. Maternal weight, height and skinfold thickness (triceps, biceps, subscapular, suprailiac and mid thigh) were measured at each visit. Maternal fat mass was estimated from the conversion of the first four skinfold thicknesses. Maternal waist and hip circumferences were also measured at the first visit and 6 weeks and 6 months postpartum. Weight and fat gain during pregnancy (13-36 weeks gestation) was 10.9 (SD 4.7) kg and 4.6 (SD 3.3) kg (P < 0.001) respectively. A significant increase in fat mass from 13 weeks gestation to 6-months postpartum was observed (2.6 (SD 4.5), P < 0.001). The increased weight at 6-months postpartum, however, was not statistically significant (1.1 (SD 6.0) kg, P = 0.20). Based on BMI in early pregnancy, the subjects were divided into groups of underweight, normal weight, overweight and obese. The last three groups were compared using ANOVA. The obese group showed a significant difference in the pattern of changes in the skinfold thickness, waist:hip ratio and fat mass at the postpartum period, in comparison with the other two groups. In conclusion, there is a tendency in the obese group to develop central obesity at the postpartum period.

Carbohydrate and lipid metabolism in pregnancy: normal compared with gestational diabetes mellitus

This article reviews maternal metabolic strategies for accommodating fetal nutrient requirements in normal pregnancy and in gestational diabetes mellitus (GDM). Pregnancy is characterized by a progressive increase in nutrient-stimulated insulin responses despite an only minor deterioration in glucose tolerance, consistent with progressive insulin resistance. The hyperinsulinemic-euglycemic glucose clamp technique and intravenous-glucose-tolerance test have indicated that insulin action in late normal pregnancy is 50-70% lower than in nonpregnant women. Metabolic adaptations do not fully compensate in GDM and glucose intolerance ensues. GDM may reflect a predisposition to type 2 diabetes or may be an extreme manifestation of metabolic alterations that normally occur in pregnancy. In normal pregnant women, basal endogenous hepatic glucose production (R(a)) was shown to increase by 16-30% to meet the increasing needs of the placenta and fetus. Total gluconeogenesis is increased in late gestation, although the fractional contribution of total gluconeogenesis to R(a), quantified from (2)H enrichment on carbon 5 of glucose (65-85%), does not differ in pregnant women after a 16-h fast. Endogenous hepatic glucose production was shown to remain sensitive to increased insulin concentration in normal pregnancy (96% suppression), but is less sensitive in GDM (80%). Commensurate with the increased rate of glucose appearance, an increased contribution of carbohydrate to oxidative metabolism has been observed in late pregnancy compared with pregravid states. The 24-h respiratory quotient is significantly higher in late pregnancy than postpartum. Recent advances in carbohydrate metabolism during pregnancy suggest that preventive measures should be aimed at improving insulin sensitivity in women predisposed to GDM. Further research is needed to elucidate the mechanisms and consequences of alterations in lipid metabolism during pregnancy.

Fat mass deposition during pregnancy using a four-component model

Estimates of body fat mass gained during human pregnancy are necessary to assess the composition of gestational weight gained and in studying energy requirements of reproduction. However, commonly used methods of measuring body composition are not valid during pregnancy. We used measurements of total body water (TBW), body density, and bone mineral content (BMC) to apply a four-component model to measure body fat gained in nine pregnant women. Measurements were made longitudinally from before conception; at 8-10, 24-26, and 34-36 wk gestation; and at 4-6 wk postpartum. TBW was measured by deuterium dilution, body density by hydrodensitometry, and BMC by dual-energy X-ray absorptiometry. Body protein was estimated by subtracting TBW and BMC from fat-free mass. By 36 wk of gestation, body weight increased 11.2 +/- 4.4 kg, TBW increased 5.6 +/- 3.3 kg, fat-free mass increased 6.5 +/- 3.4 kg, and fat mass increased 4.1 +/- 3.5 kg. The estimated energy cost of fat mass gained averaged 44,608 kcal (95% confidence interval, -31, 552-120,768 kcal). The large variability in the composition of gestational weight gained among the women was not explained by prepregnancy body composition or by energy intake. This variability makes it impossible to derive a single value for the energy cost of fat deposition to use in estimating the energy requirement of pregnancy.

Longitudinal assessment of energy balance in well-nourished, pregnant women

BACKGROUND

Clinicians often recommend an additional energy intake of 1250 kJ/d to their pregnant patients. Previous studies have shown considerable variation in the metabolic response to pregnancy and thus in the additional energy required to support a pregnancy.

OBJECTIVE

The purpose of this study was to assess how well-nourished women meet the energy demands of pregnancy and to identify factors that predict an individual's metabolic response.

DESIGN

Resting metabolic rate (RMR), diet-induced thermogenesis (DIT), total energy expenditure (TEE), activity energy expenditure (AEE), energy intake (EI), and body fat mass (FM) were measured longitudinally in 10 women preconception; at 8-10, 24-26, and 34-36 wk of gestation; and 4-6 wk postpartum.

RESULTS

Compared with preconception values, individual RMRs increased from 456 to 3389 kJ/d by late pregnancy. DIT varied from -266 to 110 kJ/meal, TEE from -105 to 3421 kJ/d, AEE from -2301 to 2929 kJ/d, EI from -259 to 2176 kJ/d, and FM from a 0.6-kg loss to a 10.6-kg gain. The only prepregnant factor that predicted FM gain was RMR (r = 0.65, P < 0.05). Women with the largest cumulative increase in RMR deposited the least FM (r = -0.64, P < 0.05).

CONCLUSIONS

Well-nourished women use different strategies to meet the energy demands of pregnancy, including reductions in DIT or AEE, increases in EI, and deposition of less FM than anticipated. The combination of strategies used by individual women is not wholly predictable from prepregnant indexes. The use of a single recommendation for increased energy intake in all pregnant women is not justified.

Adjustments in energy expenditure and substrate utilization during late pregnancy and lactation

BACKGROUND

Metabolic adjustments occur during pregnancy and lactation to support fetal growth and milk synthesis; however, the effect of body composition and hormonal milieu on these changes is poorly understood.

OBJECTIVE

We hypothesized that energy metabolism changes during pregnancy and lactation to support fetal growth and milk synthesis, and that body composition and hormonal milieu influence these alterations.

DESIGN

We measured energy expenditure, body composition, and hormone, metabolite, and catecholamine concentrations in 76 women (40 lactating, 36 nonlactating) at 37 wk gestation and 3 and 6 mo postpartum. Total energy expenditure (TEE), basal metabolic rate (BMR), sleeping metabolic rate (SMR), and minimal SMR (MSMR) were measured with room calorimetry. Fat-free mass (FFM) and fat mass were estimated with a 4-component model.

RESULTS

TEE, BMR, SMR, and MSMR were 15-26% higher during pregnancy than postpartum after being adjusted for FFM, fat mass, and energy balance. TEE, SMR, and MSMR were higher in lactating than in nonlactating women. Fasting serum insulin, insulin-like growth factor I, fatty acids, and leptin, and 24-h urinary free norepinephrine, epinephrine, and dopamine correlated positively with TEE, BMR, SMR, and MSMR. In nonlactating women, the respiratory quotient decreased over time, carbohydrate oxidation decreased, and fat oxidation increased. Substrate utilization was not influenced by body composition, fasting serum hormones, or 24-h urinary catecholamines.

CONCLUSIONS

These results indicate increased energy expenditure and preferential use of carbohydrates during pregnancy and lactation. Elevated respiratory quotient and carbohydrate utilization during pregnancy continue during lactation, consistent with preferential use of glucose by the fetus and mammary gland.

Nutritional assessment and support during pregnancy

Proper nutrition during pregnancy is critically important to mother and fetus. For most healthy women, the only nutritional intervention required may be adequate iron and folate intake; however, for others, who begin pregnancy in a malnourished state or whose nutritional intake deteriorates during pregnancy, invasive nutritional support, including tube feeding or parenteral nutrition, may be indicated. To guide nutritional therapy and to avoid its potential complications, it is necessary to evaluate the patient's nutritional state. Such evaluation must focus not only on body composition and substrate reserves but also on the patient's changing nutrient requirements and any impediments to the patient's capacity to ingest and assimilate food.

Low-sodium diet in pregnancy: effects on blood pressure and maternal nutritional status

In ninety-four Dutch nulliparous women the effects of a low-Na diet in pregnancy on blood pressure, energy and nutrient intake, Ca metabolism, Zn and Mg status and body composition were studied longitudinally. The women were randomly divided into an intervention group (n 41), which used a low-Na diet (mean urinary Na excretion 61 mmol/24 h) from week 14 of pregnancy until delivery and a control group (n 53; mean urinary Na excretion 142 mmol/24 h). No effect of the diet on blood pressure was observed. The use of a low-Na diet resulted in significantly reduced intakes of energy, protein, carbohydrates, fat, Ca, Zn, Mg, Fe and cholesterol. However, the women on the low-Na diet appeared to be able to adapt quite well to the reduced intake since Ca, Zn and Mg homeostasis was maintained. In the case of Ca and Mg this was probably due to the observed reduced urinary excretions of these nutrients. Non-significant reductions in weight gain (1.5 kg) and fat-mass gain (0.9 kg) over pregnancy were found in the women on the low-Na diet. No significant effects of the diet on birth weight or placental weight were observed.

Unexpected relationship between fat mass and basal metabolic rate in pregnant women

We investigated the relationships between BMR, fat-free mass (FFM) and fat mass in pregnancy. BMR was measured by indirect calorimetry and body composition was assessed by densitometry in seventeen non-pregnant women (79.9 (SD 26.3, range 50.5-151.4) kg) and sixteen pregnant women (75.7 (SD 20.6, range 54.5-115.9) kg). The pregnant women were evaluated during weeks 31-35 of gestation. Multiple regression analysis of BMR with FFM and fat mass in the non-pregnant women showed that FFM was a highly significant predictor of BMR (P < 0.0001), but fat mass was not (P = 0.09). In contrast, in the pregnant women, multiple regression analysis revealed that fat mass was a highly significant predictor (P < 0.001), while FFM was not (P = 0.69). Evaluation of the interaction terms in the combined data set confirmed that the relationships of BMR with FFM and fat mass differ significantly in non-pregnant and pregnant women. It is proposed that pregnancy represents a unique condition during which BMR is regulated by maternal adipose reserves. An augmented BMR in overweight pregnant women may be protective, given that excessive weight gain may be detrimental to neonatal and maternal health.

Energy requirements of pregnancy for healthy Dutch women

Over the past 15 years we have performed several longitudinal studies with healthy Dutch women, in which components of an energy balance were measured before, during and after pregnancy. The observed small changes in energy intake over pregnancy are insufficient to meet the energy costs of pregnancy. This suggests that substantial savings were made on energy expenditure. We found no evidence for improvement of digestibility, for lower energy costs in ingesting, absorbing, transporting and storing nutrients, or for lower energy costs for performing fixed-paced physical tasks. So, it appears that our Dutch women cannot increase the efficiency of their energy metabolism. However we could clearly demonstrate that our women reduced their daily energy expenditure by decreasing the amount and pace of physical activity. In summary, our studies suggest there is no need for well-nourished western women to increase food intake in pregnancy, provided that the mothers reduce their level of physical activity. However, since the requirements for specific nutrients are increased in pregnancy, special attention should be given to the quality of the diet.

No substantial reduction of the thermic effect of a meal during pregnancy in well-nourished Dutch women

To investigate changes in the thermic effect of a meal (TEM) during pregnancy, metabolic rate was measured in the fasting state and during the first 180 min after consumption of a standardized test meal in twenty-seven women before, and in each trimester of pregnancy. Resting metabolic rate (RMR) showed a steady increase over pregnancy: values in weeks 24 and 35 of pregnancy were significantly higher than the prepregnancy baseline (Tukey's studentized range test). The pattern of changes of postprandial metabolic rate (PPMR) was similar to that of RMR. Consequently TEM, calculated as PPMR minus RMR, did not change over pregnancy; mean TEM values (kJ/180 min) before and in weeks 13, 24 and 35 of pregnancy were 117.3 (SD 19.4), 116.4 (SD 23.7), 111.6 (SD 24.4) and 111.5 (SD 26.7) respectively. We consider changes in TEM of less than 15% to be of little importance physiologically. If true changes in TEM over pregnancy are 15% or more we would have had a 90% chance of observing significant changes in TEM in the present study, given the number of subjects and the methods used. Therefore, we conclude that no substantial reduction in TEM occurs during pregnancy.

Insulin insensitivity is associated with a decrease in postprandial thermogenesis in normal pregnancy

Insulin sensitivity and postprandial thermogenesis were investigated at various stages of pregnancy to assess if changes in insulin sensitivity contribute to energy conservation during pregnancy. Cross-sectional and longitudinal studies were undertaken. Sixteen control non-pregnant women were compared with 10 women in the second trimester (2nd) and thirteen women in the third trimester (3rd) of uncomplicated pregnancy. Six women were studied at all three time points. The slope of plasma glucose decline following a bolus of intravenous insulin was used as an index of insulin sensitivity. Resting energy expenditure was measured with continuous indirect calorimetry. Postprandial thermogenesis was measured as the change in energy expenditure for the 2 h after a mixed meal. Results are expressed as mean +/- SEM or median (interquartile range). Insulin sensitivity was lower as pregnancy progressed (non-pregnant control 181 (177-205) vs 2nd 111 (100-112) vs 3rd 96 (80-109) mumol l-1 min-1, p < 0.001). Fasting insulin levels were significantly higher in the third trimester but not in the second trimester (non-pregnant control 1.9 (1.5-6.0) vs 2nd 3.1 (2.8-5.2) vs 3rd 8.6 (4.8-9.7) mU l-1, p < 0.05). Meal stimulated insulin levels were higher in the second and third trimesters compared to non-pregnant women (insulin area over 2 h, postmeal, non-pregnant control 78 +/- 10 vs 2nd 92 +/- 14 vs 3rd 145 +/- 14 mU l-1 h-1, p < 0.005). Postprandial thermogenesis was lowest in the third trimester (non-pregnant control 103 +/- 5 vs 2nd 74 +/- 8 vs 3rd 48 +/- 8 kJ, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of fat and fat-free mass deposition during pregnancy on birth weight

OBJECTIVES

The purposes of our study were to describe the patterns and location of fat and fat-free mass deposition during pregnancy and to evaluate their effects on fetal growth.

STUDY DESIGN

Our study is a prospective follow-up of 105 healthy pregnant women who were delivered of term infants. Body composition was evaluated eight times during gestation with anthropometric measures and bioimpedance techniques. Body fat and fat-free mass were calculated with equations specifically developed for this population.

RESULTS

Total weight gain was 10.0 +/- 3.5 kg; net weight gain was 3.7 +/- 0.31 kg; birth weight was 3211 +/- 467 gm (values are mean +/- SEM). In these women fat was deposited mostly in the thigh and subscapular region for a total of 6.23 +/- 0.19 kg at term. The period of pregnancy of the largest maternal fat deposition per week is between the twentieth and thirtieth weeks. After adjusting by prepregnancy weight, birth weight is associated with maternal changes in thigh skin folds and fat gain before the thirtieth week of gestation. Infants born to mothers with low fat gain before the thirtieth week were 204 gm lighter than infants born to mothers with fat gain > or = 25th percentile of this population.

CONCLUSION

Maternal nutritional status at the beginning of gestation and the rate of fat gain early in pregnancy are the two nutritional indicators most strongly associated with fetal growth in this population.

Leucine kinetics and fuel utilization during a brief fast in human pregnancy

To examine proteolysis, protein and leucine oxidation, and fuel utilization during a brief fast (approximately 17 hours) in human pregnancy, we determined leucine kinetics, urea nitrogen excretion, and respiratory quotient (RQ) in 11 pregnant subjects during the second half of gestation, and in 11 normal nonpregnant controls. The total rate of appearance (Ra) of leucine was similar in the pregnant and control groups (pregnant 4.99 +/- 0.60 v control 5.25 +/- 1.60 mmol/h [mean +/- SD]). However, leucine Ra per kilogram was significantly lower in pregnant subjects (pregnant 68 +/- 7 v control 82 +/- 13 mumol/kg/h, P less than .01). In addition, urinary urea nitrogen excretion was also significantly less in pregnant subjects (pregnant 3.74 +/- 1.09 v control 5.58 +/- 1.6 mg/kg/h, P less than .01). The RQ measured in the pregnant group was significantly higher than controls (0.82 +/- 0.05 v 0.76 +/- 0.04, P = .01), resulting in higher calculated carbohydrate oxidation rates during fasting in pregnancy. These data suggest that total rates of proteolysis (reflected by leucine flux) are similar in pregnant and nonpregnant subjects after an overnight fast. When normalized to body weight, proteolysis is lower in pregnant subjects. Urea excretion rates are also lower in pregnancy. These findings support the hypothesis that there is a pregnancy-induced adaptation to conserve maternal protein stores during a brief fast. The higher rate of carbohydrate oxidation during fasting in pregnancy may be a reflection of the fetal-placental unit's use of glucose as its predominant oxidative substrate.