Anthropometric equations for studying body fat in pregnant women

Anthropometric Changes During Pregnancy and Their Association with Adequacy of Gestational Weight Gain

Background

Gestational weight gain (GWG) is an expected component of a healthy pregnancy. Gaining weight within the recommended range helps support the mother's health by providing energy reserves and nutrients to meet the increased metabolic demands during pregnancy. Too much or too little GWG has been associated with adverse health outcomes for the mother and child.

Objective

The objective of the study was to examine how changes in anthropometric indicators during pregnancy, including fat gain, vary, compare changes among body mass index (BMI) (kg/m2) groups, and examine how the changes were associated with adequacy of GWG defined using the 2009 Institute of Medicine guidelines.

Methods

Data came from a cohort of 360 pregnant women with measured anthropometric indicators (weight, midupper arm circumference, and skin folds of the triceps, thigh, and upper iliac) at <12-, 16 to 22-, and 28 to 32-wks of gestation. Fat gain was calculated using a formula. Analysis of variance was used to test for differences in anthropometric changes by BMI and adequacy of GWG in the third trimester. Multiple logistic regression was used to examine associations between changes in anthropometric indicators and GWG recommendations.

Results

Women with normal weight had greater increases in all anthropometric indicators, which differed from women with obesity, who had negative changes and gained less weight. Women who gained inadequately (21%) had negative changes that were all less, compared with women who gained adequately (46%) (except in upper iliac) or excessively (34%). Women with BMI of >25 who gained adequately also had negative changes. Logistic regression results indicated that changes in midupper arm circumference, triceps, and thigh skin folds, and fat gain were all inversely associated with inadequate GWG, whereas all indicators were positively associated with excessive GWG.

Conclusions

Anthropometric changes during pregnancy differ by BMI and are associated with adequacy of GWG. Women who gained adequately had minimal fat gain, lending support for current GWG guidelines.

Exploring comparative assessment of adiposity measures during pregnancy and postpartum

BACKGROUND & AIMS

Excessive adiposity in pregnancy is associated with an altered cardiometabolic profile and adverse maternal and offspring outcomes. Pre-pregnancy body mass index (pBMI) is a proxy measure for adiposity that is most often used in clinical settings; however, it may not identify at-risk pregnancies caused by adiposity-related cardiometabolic dysfunction. The challenge is that validated direct adiposity measures are limited due to the dynamic nature of pregnancy. This exploratory analysis aimed to, 1) evaluate longitudinal changes in % body fat (BF) and the agreement between skinfold thickness (SFT) and bioelectrical impedance analysis (BIA) across pregnancy and in postpartum; 2) compare the discrimination power of SFT, BIA, and pBMI regarding adiposity status; and 3) assess agreement between SFT and BIA with dual-energy X-ray absorptiometry (DXA) in the postpartum.

METHODS

Participants enrolled in the Be Healthy in Pregnancy (BHIP) RCT (NCT01693510) had demographic data and pBMI collected at enrollment and adiposity measured at 12-17, 26-28, and 36-38 weeks gestation by BIA (%BF) and SFT (sum and %BF), and also by DXA at 6 months postpartum. Agreement between methods was assessed by Bland Altman plots and McNemar's test and C-statistic for discriminative power.

RESULTS

In 181 women with mean pBMI of 25.1 kg/m² (min: 17.4 kg/m², max: 39.6 kg/m²) and age 31.6 (SD: 4.0 yr), maternal adiposity increased significantly (p < 0.001) across pregnancy when measured by the sum of SFT or %BF by BIA, but not %BF by SFT. In early pregnancy, BF by BIA and SFT showed good agreement, with BIA values 1.8% greater than SFT, but low agreement in late pregnancy, with BIA values 7.1% greater than SFT. However, in the postpartum, agreement was similar to early pregnancy, and both BIA and SFT demonstrated good agreement with DXA. By pBMI, 45.5% of participants were categorized as overweight/obese, compared to 66.5% by BIA (p < 0.0001) and 54.5% by SFT (p < 0.0001).

CONCLUSIONS

In comparison to SFT and BIA, the results suggest that pBMI is less sensitive in identifying participants with excessive adiposity, limiting its use as a screening tool for adiposity-related adverse outcomes in pregnancy. It would be preferable to use a direct measure of adiposity to screen for at-risk pregnancies. Both %BF by BIA and sum of SFT can quantify the change in adiposity across pregnancy and in the postpartum and thus could be adopted as clinical practice tools. Future research efforts should further refine and validate adiposity techniques for use, particularly in mid and late pregnancy.

CLINICAL TRIAL

The BHIP clinical trial (NCT01693510). REGISTRATION SITE: https://clinicaltrials.gov/ct2/show/NCT01693510.

Associations of ultra-processed food intake with maternal weight change and cardiometabolic health and infant growth

BACKGROUND

Excessive intake of ultra-processed foods, formulated from substances extracted from foods or derived from food constituents, may be a modifiable behavioral risk factor for adverse maternal and infant health outcomes. Prior work has predominately examined health correlates of maternal ultra-processed food intake in populations with substantially lower ultra-processed food intake compared to the US population. This longitudinal study investigated relations of ultra-processed food intake with maternal weight change and cardiometabolic health and infant growth in a US cohort.

METHODS

Mothers in the Pregnancy Eating Attributes Study were enrolled at ≤12 weeks gestation and completed multiple 24-Hour Dietary Recalls within six visit windows through one-year postpartum (458 mothers enrolled, 321 retained at one-year postpartum). The NOVA (not an acronym) system categorized food and underlying ingredient codes based on processing level. Maternal anthropometrics were measured throughout pregnancy and postpartum, and infant anthropometrics were measured at birth and ages 2 months, 6 months, and 1 year. Maternal cardiometabolic markers were analyzed from blood samples obtained during the second and third trimesters.

RESULTS

Holding covariates and total energy intake constant, a 1-SD greater percent energy intake from ultra-processed foods during pregnancy was associated with 31% higher odds of excessive gestational weight gain (p = .045, 95% CI [1.01, 1.70]), 0.68±0.29 mg/L higher c-reactive protein during pregnancy (p = .021, 95% CI [0.10, 1.26]), 6.7±3.4% greater gestational weight gain retained (p = .049, 95% CI [0.03, 13.30]), and 1.09±0.36 kg greater postpartum weight retention (p = .003, 95% CI [0.38, 1.80]). No other significant associations emerged.

CONCLUSIONS

Ultra-processed food intake during pregnancy may be a modifiable behavioral risk factor for adverse maternal weight outcomes and inflammation. Randomized controlled trials are needed to test whether targeting ultra-processed food intake during pregnancy may support optimal maternal health.

TRIAL REGISTRATION

Clinicaltrials.gov. Registration ID - NCT02217462 . Date of registration - August 13, 2014.

Maternal anthropometric measurements and correlation to maternal and fetal outcomes in late pregnancy

Background:

Body mass index does not distinguish between lean and fat body mass; therefore, its utility defining body composition is limited in pregnancy. Anthropometric measurements may better represent variation in body composition among women who are overweight or obese. We sought to examine body fat composition using maternal anthropometric measurements in late pregnancy and correlate with mode of delivery.

Methods:

A prospective study of pregnant patients who were overweight (body mass index: 25–29.9 kg/m²) or obese (body mass index ⩾ 30 kg/m²) with singleton pregnancies who underwent anthropometric measurements between 27 weeks, 0 days to 34 weeks, 6 days gestation. Maternal skinfold thicknesses from eight sites were used to estimate body fat mass. Correlation of skinfold thickness, anthroprometric measurements, and estimated body fat percentage on mode of delivery were analyzed with p < .05 as significant.

Results:

A total of 41 women with overweight (34.1%) or obese (65.9%) body habitus were included. Mean age was 29.9 years, and the majority (43.9%) were Black and 31.7% identified Hispanic/Latinx. The average gestational age at recruitment was 30 weeks, 2 days and 38 weeks, 6 days at delivery. A greater weight at recruitment (94.2 vs 81.8 kg, p = .023), waist circumference (47.1 vs 43.5 inches, p = .010), Huston–Presley body fat percentage (36.4% vs 31.8%, p = .030), triceps skinfold thickness (20.1 vs 15.7 mm, p = .030), biceps skinfold thickness (18.6 vs 15.0 mm, p = .042), and skinfold thickness, as well as sum of skinfold sites (83.3 vs 68.8 mm, p = .049) were associated with cesarean delivery compared to vaginal delivery on univariate analysis.

Conclusion:

Third-trimester anthropometric measurements may help predict increased risk for c-section in women with obesity. Further research may elucidate utility in nutritional counseling and delivery planning.

Analysis and Reliability of Anthropometric Measurements during Pregnancy: A Prospective Cohort Study in 208 Pregnant Women

Anthropometric assessment during pregnancy is a widely used, low-technology procedure that has not been rigorously evaluated. Our objective is to investigate fat mass distribution during pregnancy by examining changes in anthropometrics measures, in order to evaluate the reliability of these measures. An observational, longitudinal, prospective cohort study was performed in 208 pregnant women. Anthropometric measurements were taken following the ISAK protocol during the three trimesters and a generalized linear model for repeated measures was used to evaluate differences. Variability was assessed using the coefficient of variation, and Propagated Error (PE) was used to sum of skinfold thicknesses (SFT). SFT showed a general increase in fat mass during the three trimesters of pregnancy (∑SFT7 p = 0.003), and was observed in specific anatomical locations as well: arms (∑Arm SFT, p = 0.046), trunk (∑Trunk SFT, p = 0.019), legs (∑Leg SFT, p = 0.001) and appendicular (∑Appendicular SFT, p = 0.001). Anthropometric measures for skinfold thickness were taken individually during pregnancy and were reliable and reproducible during the three trimesters, which could help to prevent adverse pregnancy outcomes.

Maternal adiposity is associated with inflammatory gene expression in leukocytes at term human pregnancy: A pilot study

Background

Human labor is associated with an inflammatory process that takes place at the maternal–fetal interface, where leukocytes infiltrate and contribute to the local production of effector molecules such as cytokines, chemokines, MMPs, etc. This process may be altered by a low‐grade chronic inflammation, characteristic of obesity, resulting in adverse pregnancy outcomes. In this cross‐sectional pilot study, we analyzed the relationship between maternal adiposity and inflammation‐related gene expression in leukocytes from six healthy women with term pregnancies without labor.

Methods

We estimated maternal adiposity and examined the relative expression of 211 inflammation‐related genes in maternal peripheral blood leukocytes (MAT), placental intervillous blood leukocytes (PLA), and choriodecidual leukocytes (CHD) by real‐time qPCR. Finally, we analyzed the correlation between maternal adiposity and gene expression.

Results

Participants’ adiposity ranged from 27.6% to 61.1% (n = 6). The expression of 23 genes significantly differed (p < 0.05) in MAT, PLA, and CHD leukocytes, most of which code for chemokines and proinflammatory cytokines. Importantly, increasing maternal adiposity correlated (r > 0.7) mostly positively with the expression of genes related to activation, migration, infiltration, and proinflammation in MAT (36 genes) and PLA (31 genes). In contrast, in CHD leukocytes maternal adiposity correlated only negatively with seven genes, involved in migration and infiltration.

Conclusion

Our findings suggest that during term pregnancy, increased maternal adiposity may enhance the priming of peripheral leukocytes, while in choriodecidua it may alter leukocyte recruitment and proinflammatory activity. Maternal adiposity must be considered an important variable in further studies that analyze inflammation‐related gene expression in pregnant women.

Reward-related eating, self-regulation, and weight change in pregnancy and postpartum: the Pregnancy Eating Attributes Study (PEAS)

Background/Objectives.

Reward-related eating is hypothesized to underlie risk for weight gain in obesogenic environments, but its role is unknown during pregnancy and postpartum when weight change is normative, but excess weight gain and weight retention are common. This study examined associations of self-reported reward-related eating, self-regulation, and the home food environment with excessive gestational weight gain (GWG) and postpartum weight change.

Subjects/Methods.

Participants in the Pregnancy Eating Attributes Study observational cohort were enrolled at ≤12 weeks pregnancy and followed through one-year postpartum (458 recruited; 367 retained through delivery). Participants completed four measures of reward-related eating – Modified Yale Food Addiction Scale, Power of Food Scale, Multiple Choice Procedure, and a Reinforcing Value of Food Questionnaire; two measures of self-regulation – Barratt Impulsiveness Scale and Delay of Gratification Inventory; and a Home Food Inventory. Measured weight and skinfolds were obtained. Multinomial logistic and multiple linear regression analyses estimated associations of reward-related eating, self-regulation, and home food environment with excessive GWG, gestational fat gain, postpartum weight change, and percent of GWG retained.

Results.

Excessive GWG was associated with food reinforcement intensity, but not with any other measure of reward-related eating, self-regulation, or home food environment. Greater gestational fat gain was associated only with higher Multiple Choice Procedure. Postpartum weight change and percent of GWG retained were associated with greater Delay of Gratification and obesogenic home food environment, but not with any measure of reward-related eating or with impulsivity.

Conclusions.

Findings do not support the hypothesis that self-reported reward-related eating is associated with weight outcomes in pregnancy and postpartum but indicate a relation of Delay of Gratification with postpartum weight retention. Further research using both surveys and objective measures of reward-related eating is needed to advance our understanding of the relation of reward-related eating with weight changes during this critical period of a woman’s life.

A Prospective Study of the Relationship of Sleep Quality and Duration with Gestational Weight Gain and Fat Gain

Objective/Background: Fewer than one-third of U.S. women meet the Institute of Medicine guidelines for healthy gestational weight gain (GWG). While poor sleep quality and short sleep duration have been associated with weight gain and obesity in the general population, the relationship of sleep with pregnancy weight and body composition changes is unclear. This study aimed to examine associations of sleep duration and quality with pregnancy-related changes in body weight and fat. Participants: Pregnant women obtaining obstetric care through the University of North Carolina at Chapel Hill Healthcare System (UNC) (n = 339 who reported any sleep data) participating in the Pregnancy Eating Attributes Study. Materials and Methods: Participants were recruited at ≤12 weeks gestation and followed through delivery. The Pittsburgh Sleep Quality Index measured sleep duration and quality in early and late pregnancy. Weight was measured at each pregnancy medical visit and skinfolds were measured each trimester. t-tests examined sleep changes from early to late pregnancy and regression analyses estimated associations of sleep quality and duration with GWG and gestational fat gain (GFG). Results: Sleep quality and duration declined across pregnancy. A greater proportion of women with high early pregnancy body mass index (>25) reported low sleep quality and short sleep duration. Sleep quality was not associated with GWG adequacy, whereas longer late pregnancy sleep duration was associated with greater odds of inadequate GWG. Shorter sleep duration and lower sleep quality in late, but not early, pregnancy were associated with greater GFG. Conclusions: Lower sleep quality and shorter sleep duration in late pregnancy were associated with greater GFG. Experimental studies are needed to test the direction of causality between GFG and sleep attributes. ClinicalTrials.gov ID: NCT02217462.

Optical imaging technology for body size and shape analysis: evaluation of a system designed for personal use

BACKGROUND/OBJECTIVES

Three-dimensional optical (3DO) imaging systems that rapidly and accurately provide body shape and composition information are increasingly available in research and clinical settings. Recently, relatively low-cost and space efficient 3DO systems with the ability to report and track individual assessments were introduced to the consumer market for home use. This study critically evaluated the first 3DO imaging device intended for personal operation, the Naked Body Scanner (NBS), against reference methods.

PARTICIPANTS/METHODS

Circumferences at six standardized anatomic sites were measured with a flexible tape in 90 participants ranging in age (5-74 years), ethnicity, and adiposity. Regression analysis and Bland-Altman plots compared these direct measurements and dual-energy X-ray absorptiometry (DXA) %fat estimates to corresponding NBS values. Method precision was analyzed from duplicate anthropometric and NBS measurements in a subgroup of 51 participants.

RESULTS

The NBS exhibited greater variation in test-retest reliability (CV, 0.4-2.7%) between the six measured anatomic locations when compared with manually measured counterparts (0.2-0.4%). All six device-derived circumferences correlated with flexible tape references (R2s, 0.84-0.97; p < 0.0001). Measurement bias was apparent for three anatomic sites while mean differences were present for five. The NBS's %fat estimates also correlated with DXA results (R2 = 0.73, p < 0.0001) with no significant bias.

CONCLUSIONS

This system opens a new era of digital home-based assessments that can be incorporated into weight loss or exercise interventions accessible to clinical investigators as well as individual users.

Gestation-Specific Changes in the Anatomy and Physiology of Healthy Pregnant Women: An Extended Repository of Model Parameters for Physiologically Based Pharmacokinetic Modeling in Pregnancy

BACKGROUND

In the past years, several repositories for anatomical and physiological parameters required for physiologically based pharmacokinetic modeling in pregnant women have been published. While providing a good basis, some important aspects can be further detailed. For example, they did not account for the variability associated with parameters or were lacking key parameters necessary for developing more detailed mechanistic pregnancy physiologically based pharmacokinetic models, such as the composition of pregnancy-specific tissues.

OBJECTIVES

The aim of this meta-analysis was to provide an updated and extended database of anatomical and physiological parameters in healthy pregnant women that also accounts for changes in the variability of a parameter throughout gestation and for the composition of pregnancy-specific tissues.

METHODS

A systematic literature search was carried out to collect study data on pregnancy-related changes of anatomical and physiological parameters. For each parameter, a set of mathematical functions was fitted to the data and to the standard deviation observed among the data. The best performing functions were selected based on numerical and visual diagnostics as well as based on physiological plausibility.

RESULTS

The literature search yielded 473 studies, 302 of which met the criteria to be further analyzed and compiled in a database. In total, the database encompassed 7729 data. Although the availability of quantitative data for some parameters remained limited, mathematical functions could be generated for many important parameters. Gaps were filled based on qualitative knowledge and based on physiologically plausible assumptions.

CONCLUSION

The presented results facilitate the integration of pregnancy-dependent changes in anatomy and physiology into mechanistic population physiologically based pharmacokinetic models. Such models can ultimately provide a valuable tool to investigate the pharmacokinetics during pregnancy in silico and support informed decision making regarding optimal dosing regimens in this vulnerable special population.

Advances in assessing body composition during pregnancy

The prevalence of excess gestational weight gain is increasing worldwide and is associated with pregnancy complications, including gestational diabetes mellitus, pre-eclampsia, preterm birth, macrosomia, and development of obesity in offspring. Whereas gestational weight gain positively correlates with the gain in fat mass (FM), fat-free mass (FFM) gain is relatively consistent across pregnancies. Commonly used methods to assess body composition include anthropometry, densitometry (air displacement plethysmography, underwater weighing), and hydrometry (isotope dilution, bioimpedance analysis). While these techniques can be applied to pregnancy, they require specific adjustments to assumptions inherent within each method, most importantly to accommodate for the hydration of FFM which is transient throughout gestation. Here we discuss the application of the abovementioned methods to pregnant women and the relevant adjustments needed to more accurately calculate FM based on body weight, body volume, or total body water. We also present a novel application of classical data to provide FFM density estimates for pregnant women at any stage of pregnancy. Use of these adjustments will help standardize assumptions on FFM hydration and minimize error in FM estimation. Techniques still fail, however, to fully distinguish tissue gains between mother and fetus. To fill this important gap, imaging techniques such as ultrasound and magnetic resonance imaging are being used more frequently and will provide more insight into fetal development, fetal adiposity, and depot specificity of maternal FM acquisition. Efforts to synchronize protocols are necessary to allow seamless comparison of data to advance the understanding of maternal body composition changes that contribute to pregnancy-related complications.

Clinically applicable optical imaging technology for body size and shape analysis: comparison of systems differing in design

BACKGROUND/OBJECTIVES

Recent advances have extended anthropometry beyond flexible tape measurements to automated three-dimensional optical devices that rapidly acquire hundreds of body surface dimensions. Three new devices were recently introduced that share in common inexpensive optical cameras. The design, and thus potential clinical applicability, of these systems differ substantially leading us to critically evaluate their accuracy and precision.

SUBJECTS/METHODS

113 adult subjects completed evaluations by the three optical devices (KX-16 (16 stationary cameras), Proscanner (1 vertically oscillating camera), and Styku scanner (1 stationary camera)), air displacement plethysmography (ADP), dual-energy X-ray absorptiometry (DXA) and a flexible tape measure. Optical measurements were compared to reference method estimates that included results acquired by flexible tape, DXA and ADP.

RESULTS

Optical devices provided respective circumference and regional volume estimates that overall were well-correlated with those obtained from flexible tape measurements (for example, hip circumference: R2, 0.91, 0.90, 0.96 for the KX-16, Proscanner, and Styku scanner, respectively) and DXA (for example, trunk volume: R2, 0.97, 0.97, and 0.98). Total body volumes measured by the optical devices were highly correlated with those from the ADP system (all R2s, 0.99). Coefficient of variations obtained from duplicate measurements (n, 55) were larger in optical than in reference measurements and significant (P<0.05) bias was present for some optical measurements relative to reference method estimates.

CONCLUSIONS

Overall, the evaluated optical imaging systems differing in design provided body surface measurements that compared favorably with corresponding reference methods. However, our evaluations uncovered system measurement limitations, such as discrepancies in landmarking, that with correction have the potential to improve future developed devices.

The Pattern of Gestational Weight Gain is Associated with Changes in Maternal Body Composition and Neonatal Size

OBJECTIVES

The pattern of gestational weight gain (GWG) reflects general nutrient availability to support growing fetal and maternal compartments and may contribute to later health, but how it relates to changes in maternal body composition is unknown. We evaluated how the pattern of GWG related to changes in maternal body composition during pregnancy and infant size at birth.

METHODS

A prospective, multi-ethnic cohort of 156 pregnant women and their infants was studied in New York City. Prenatal weights were used to estimate total and rate (kg/week) of GWG by trimester. Linear regression models evaluated the association between trimester-specific GWG group (low, medium, high GWG) [total (low ≤25, high ≥75 percentile) or rate (defined by tertiles)] and infant weight, length and maternal body composition changes from 14 to 37 weeks, adjusting for covariates.

RESULTS

Compared to the low gain group, medium/high rate of GWG in the second trimester and high rate of GWG in the third trimester were associated with larger gains in maternal fat mass (β range for fat Δ = 2.86-5.29 kg, all p < 0.01). For infant outcomes, high rate of GWG in the second trimester was associated with higher birth weight (β = 356 g, p = 0.001) and length (β = 0.85 cm, p = 0.002). First and third trimester GWG were not associated with neonatal size.

CONCLUSIONS

The trimester specific pattern and rate of GWG reflect changes in maternal body fat and body water, and are associated with neonatal size, which supports the importance of monitoring trimester-specific GWG.

Comparison of multiple methods to measure maternal fat mass in late gestation

BACKGROUND

Measurements of maternal fat mass (FM) are important for studies of maternal and fetal health. Common methods of estimating FM have not been previously compared in pregnancy with measurements using more complete body composition models.

OBJECTIVES

The goal of this pilot study was to compare multiple methods that estimate FM, including 2-, 3- and 4-compartment models in pregnant women at term, and to determine how these measures compare with FM by dual-energy X-ray absorptiometry (DXA) 2 wk postpartum.

DESIGN

Forty-one healthy pregnant women with prepregnancy body mass index (in kg/m(2)) 19 to 46 underwent skinfold thickness (SFT), bioelectrical impedance analysis (BIA), body density (Db) via air displacement plethysmography (ADP), and deuterium dilution of total body water (TBW) with and without adjustments for gestational age using van Raaij (VRJ) equations at 37-38 wk of gestation and 2 wk postpartum to derive 8 estimates of maternal FM. Deming regression analysis and Bland-Altman plots were used to compare methods of FM assessment.

RESULTS

Systematic differences in FM estimates were found. Methods for FM estimates from lowest to highest were 4-compartment, DXA, TBW(VRJ), 3-compartment, Db(VRJ), BIA, air displacement plethysmography body density, and SFT ranging from a mean ± SD of 29.5 ± 13.2 kg via 4-compartment to 39.1 ± 11.7 kg via SFT. Compared with postpartum DXA values, Deming regressions revealed no substantial departures from trend lines in maternal FM in late pregnancy for any of the methods. The 4-compartment method showed substantial negative (underestimating) constant bias, and the air displacement plethysmography body density and SFT methods showed positive (overestimating) constant bias. ADP via Db(VRJ)and 3-compartment methods had the highest precision; BIA had the lowest.

CONCLUSIONS

ADP that uses gestational age-specific equations may provide a reasonable and practical measurement of maternal FM across a spectrum of body weights in late pregnancy. SFT would be acceptable for use in larger studies. This trial was registered at clinicaltrials.gov as NCT02586714.

Influence of antenatal physical exercise on haemodynamics in pregnant women: a flexible randomisation approach

Background

Normal pregnancy is associated with marked changes in haemodynamic function, however the influence and potential benefits of antenatal physical exercise at different stages of pregnancy and postpartum remain unclear. The aim of this study was therefore to characterise the influence of regular physical exercise on haemodynamic variables at different stages of pregnancy and also in the postpartum period.

Methods

Fifity healthy pregnant women were recruited and randomly assigned (2 × 2 × 2 design) to a land or water-based exercise group or a control group. Exercising groups attended weekly classes from the 20th week of pregnancy onwards. Haemodynamic assessments (heart rate, cardiac output, stroke volume, total peripheral resistance, systolic and diastolic blood pressure and end diastolic index) were performed using the Task Force haemodynamic monitor at 12–16, 26–28, 34–36 and 12 weeks following birth, during a protocol including postural manoeurvres (supine and standing) and light exercise.

Results

In response to an acute bout of exercise in the postpartum period, stroke volume and end diastolic index were greater in the exercise group than the non-exercising control group (p = 0.041 and p = 0.028 respectively). Total peripheral resistance and diastolic blood pressure were also lower (p = 0.015 and p = 0.007, respectively) in the exercise group. Diastolic blood pressure was lower in the exercise group during the second trimester (p = 0.030).

Conclusions

Antenatal exercise does not appear to substantially alter maternal physiology with advancing gestation, speculating that the already vast changes in maternal physiology mask the influences of antenatal exercise, however it does appear to result in an improvement in a woman’s haemodynamic function (enhanced ventricular ejection performance and reduced blood pressure) following the end of pregnancy.

Trial registration

ClinicalTrials.gov NCT02503995. Registered 20 July 2015.

Maternal obesity influences the relationship between location of neonate fat mass and total fat mass

BACKGROUND

It is suggested that maternal obesity perpetuates offspring obesity to future generations.

OBJECTIVE

To determine whether location of neonate fat mass (FM: central vs. peripheral) is related to total neonate FM and whether maternal obesity influences this relationship.

METHODS

Neonate body composition and skin-fold thicknesses were assessed in healthy neonates (n = 371; 1-3 days old). Linear regression models examined the relationship between total FM and location of FM (central vs. peripheral). Location of FM was calculated by skin-folds: peripheral was the sum of (biceps and triceps)/2 and central was represented by the subscapular skin-fold.

RESULTS

A significant interaction was found for location of FM and maternal obesity. Holding all predictors constant, in offspring born to non-obese mothers, a 0.5 mm increase in central FM predicted a 15 g greater total FM, whereas a 0.5 mm increase in peripheral FM predicted a 66 g greater total FM. However, in offspring born to obese mothers, a 0.5 mm increase in central FM predicted a 56 g total FM, whereas a 0.5 mm increase in peripheral FM predicted a 14 g greater total FM.

CONCLUSIONS

The relationship between total FM and location of FM is influenced by maternal obesity.

Maternal prepregnancy waist circumference and BMI in relation to gestational weight gain and breastfeeding behavior: the CARDIA study

BACKGROUND

Studies suggest that gestational weight gain (GWG) and breastfeeding behavior may influence long-term maternal abdominal fat mass. However, this could be confounded by abdominal fat mass before pregnancy because it is unknown whether abdominal fat mass, independently of body size, affects GWG and breastfeeding behavior.

OBJECTIVE

We investigated how maternal prepregnancy fat distribution, described by waist circumference (WC) and body mass index (BMI), is associated with GWG and breastfeeding behavior.

DESIGN

We analyzed 1371 live births to 1024 women after enrollment in the Coronary Artery Risk Development in Young Adults study (1985-1996). For each birth, maternal prepregnancy BMI and WC were measured at year 0 (baseline), 2, 5, or 7 examinations. Recalled GWG and breastfeeding behavior were collected at years 7 and 10. GWG was analyzed by using linear regression and breastfeeding behavior by using logistic regression and discrete-time logistic regression.

RESULTS

Adjusted for potential confounders, a 1-cm larger WC adjusted for BMI was associated with a 0.19-kg (95% CI: -0.29-, -0.10-kg) lower GWG. In contrast, a 1-unit higher BMI adjusted for WC was associated with a 0.27-kg (95% CI: 0.06-, 0.47-kg) higher GWG. The OR for ever breastfeeding compared with never breastfeeding was 0.93 (95% CI: 0.90, 0.97) per 1-cm larger WC after adjustment for BMI, whereas it was 1.10 (95% CI: 1.02, 1.19) per 1-unit higher BMI adjusted for WC.

CONCLUSIONS

Maternal prepregnancy body size was differently associated with GWG and breastfeeding behavior depending on the location of the fat mass. Thus, maternal fat distribution may be a more important determinant of GWG and breastfeeding behavior than BMI alone.

Body composition changes in pregnancy: measurement, predictors and outcomes

Prevalence of overweight and obesity has risen in the United States over the past few decades. Concurrent with this rise in obesity has been an increase in pregravid body mass index and gestational weight gain affecting maternal body composition changes in pregnancy. During pregnancy, many of the assumptions inherent in body composition estimation are violated, particularly the hydration of fat-free mass, and available methods are unable to disentangle maternal composition from fetus and supporting tissues; therefore, estimates of maternal body composition during pregnancy are prone to error. Here we review commonly used and available methods for assessing body composition changes in pregnancy, including: (1) anthropometry, (2) total body water, (3) densitometry, (4) imaging, (5) dual-energy X-ray absorptiometry, (6) bioelectrical impedance and (7) ultrasound. Several of these methods can measure regional changes in adipose tissue; however, most of these methods provide only whole-body estimates of fat and fat-free mass. Consideration is given to factors that may influence changes in maternal body composition, as well as long-term maternal and offspring outcomes. Finally, we provide recommendations for future research in this area.

Subcutaneous body fat in pregnant New Zealand women: association with wheeze in their infants at 18 months

To investigate the association of subcutaneous body fat levels in pregnant women with wheezing in their 18 month old infants. A prospective study of European and Polynesian volunteers (n = 369) recruited from northern New Zealand were visited in months 4 and 7 of pregnancy when height, weight, and triceps, biceps and costal skinfolds were measured, and questionnaires determining personal details administered; and again visited 18 months after birth when infants were measured and questions on infant feeding and wheeze administered. At 18 months 32 % of infants had wheezed in the past 12 months. Increased wheeze was associated with maternal asthma, eczema or allergy (p = 0.001); receiving family welfare payments (p = 0.010); and being Polynesian (p = 0.021); while exclusive breastfeeding to 2 months (p = 0.045) was associated with decreased wheeze. Individual month 4 and month 7 mean triceps, biceps and costal skinfolds were all greater in mothers of wheezers compared to nonwheezers, biceps and costal skinfolds significantly so (p = 0.002, p = 0.005 at month 7). The sum of these skinfolds at month 4, at month 7, and the difference between these sums, were all significantly associated with increased risk of infant wheeze at 18 months when considered alone (p = 0.037, p = 0.001 and p = 0.015) or in combination. Prevalence of infant wheeze was 22.7 % for mothers with lower quartile month 7 skinfolds, compared to 45.0 % for mothers with upper quartile. After adjusting for significant covariates the difference in skinfolds had the strongest association (p = 0.003) followed by sum at month 4 (p = 0.074 or 0.003 depending on whether Polynesian ethnicity was included in the model). The sum of skinfolds declined between month 4 and month 7 in 34 % of women. Prevalence of wheeze was 19.2 % where the difference in mothers' skinfolds between month 4 and month 7 decreased by 10 mm or more and 41.7 % where the difference increased by 10 mm or more. Mean month 4 weights, BMI and sum of skinfolds were below average in the latter group. As the sum of month 4 or month 7 maternal skinfolds increased the prevalence of infant wheeze increased. In addition as the change in skinfolds between month 4 and month 7 became more positive the prevalence of infant wheeze increased. This study suggests for the first time that changes in subcutaneous fat during pregnancy are associated with prevalence of infant wheeze.

The relationship between maternal adiposity and infant weight gain, and childhood wheeze and atopy

BACKGROUND

Obesity and asthma have increased in westernised countries. Maternal obesity may increase childhood asthma risk. If this relation is causal, it may be mediated through factors associated with maternal adiposity, such as fetal development, pregnancy complications or infant adiposity. We investigated the relationships of maternal body mass index (BMI) and fat mass with childhood wheeze, and examined the influences of infant weight gain and childhood obesity.

METHODS

Maternal prepregnancy BMI and estimated fat mass (from skinfold thicknesses) were related to asthma, wheeze and atopy in 940 children. Transient or persistent/late wheeze was classified using questionnaire data collected at ages 6, 12, 24 and 36 months and 6 years. At 6 years, skin-prick testing was conducted and exhaled nitric oxide and spirometry measured. Infant adiposity gain was calculated from skinfold thickness at birth and 6 months.

RESULTS

Greater maternal BMI and fat mass were associated with increased childhood wheeze (relative risk (RR) 1.08 per 5 kg/m(2), p=0.006; RR 1.09 per 10 kg, p=0.003); these reflected associations with transient wheeze (RR 1.11, p=0.003; RR 1.13, p=0.002, respectively), but not with persistent wheeze or asthma. Infant adiposity gain was associated with persistent wheeze, but not significantly. Adjusting for infant adiposity gain or BMI at 3 or 6 years did not reduce the association between maternal adiposity and transient wheeze. Maternal adiposity was not associated with offspring atopy, exhaled nitric oxide, or spirometry.

DISCUSSION

Greater maternal adiposity is associated with transient wheeze but not asthma or atopy, suggesting effects upon airway structure/function but not allergic predisposition.

Changes in skinfolds and mid-upper arm circumference during pregnancy in Argentine women

This investigation describes the pattern of changes in mid-upper arm circumference (MUAC), triceps, biceps and subscapular skinfold thicknesses during the course of pregnancy, and its relationship with maternal and newborn outcomes. A prospective cohort of 1066 pregnant women were selected in seven different urban regions in Argentina. Measurements of MUAC were carried out at 16, 28 and 36 gestational weeks. In a subsample of 488 women, triceps, biceps and subscapular skinfold thicknesses were measured. Mean total increase in subscapular, tricipital and bicipital skinfolds from 16 to 36 weeks of gestation were 4.5, 3.6 and 2.6 mm, respectively. MUAC showed a mean increase of 1.7 cm in the same period. Overweight or obese women at the start of pregnancy had lower increases in all measurements compared with women with normal or low body mass index. Maternal anthropometry was related to birthweight; women who gave birth to infants of less than 3000 g had lower average values in all measurements than those who had normal birthweight infants. LMS curves for MUAC and skinfolds by gestational age are presented, which can be used as a reference to assess maternal nutrition status during pregnancy. MUAC, tricipital and subscapular skinfold for gestational age curves are proposed for monitoring maternal nutritional status during pregnancy. MUAC cut-off points of 24.5, 25.5 and 26.5 cm for 16, 28 and 36 weeks of gestation, respectively, are also proposed as a proxy to detect low birthweight.

[A Longitudinal study of body composition and basal metabolic rate during pregnancy in a black population of Kinshasa, Democratic Republic of Congo (RDC)]

OBJECTIVE

A longitudinal study of body composition and basal metabolic rate during pregnancy in a black population of Kinshasa.

MATERIALS AND METHODS

Body composition and basal metabolic rate were determined by bioimpedance, and energy intake was evaluated using the 24 h recall method at 20, 34 and > 37 weeks of gestation in 76 black, Congolese women. The subjects had to be healthy, and to deliver term, singleton infants after a normal pregnancy.

RESULTS

At 20 weeks of pregnancy, the 76 women, aged 28.5+/-6.4 years, had a body weight of 61.1+/-7.7 kg, a body mass index of 23.0+/-3.8 kg/m(2), a fat mass of 36.6+/-6.8% and a basal metabolic rate of 1399+/-84 kcal/24 h. Subsequently, increases in body weight (+6.5 kg), fat-free mass (+ 5.1 kg), body water (+4.4 l) and basal metabolic rate (+297 kcal/24 h) (P < 0.0001) were observed. The increase in fat mass (+1.4 kg) was less pronounced. Energy intake was stable.

CONCLUSION

Changes in body composition during pregnancy in Congolese black women are comparable to those reported in other populations. Pre- and per-gravidic fat mass is higher in congolese women than in Caucasian women.

Wrist circumference is related to patellar tendon thickness in healthy men and women

The efficacy of dominant wrist circumference measurements to predict dominant lower extremity patellar tendon thickness at regions of interest for bone-patellar tendon-bone (BPTB) autograft harvest was studied among 24 healthy men and women. Dominant wrist circumference displayed good relationships with dominant lower extremity patellar tendon thickness as determined by two-dimensional diagnostic ultrasound. This initial screening method may assist surgeons as they consider graft selection for patients who may be at risk for developing or exacerbating preexisting patellofemoral joint or knee extensor mechanism conditions with BPTB autograft harvest.

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.

Breastfeeding and postpartum weight retention in a cohort of Brazilian women

BACKGROUND

The relation between postpartum weight retention and breastfeeding practices is controversial.

OBJECTIVE

Defining breastfeeding as the period when a child is exclusively or predominantly breastfed, we studied the association between breastfeeding duration and postpartum weight retention.

DESIGN

We followed 405 women aged 18-45 y who were assessed at 0.5, 2, 6, and 9 mo postpartum. The outcome variable, postpartum weight retention, was expressed as the difference between the observed weight at each follow-up and the reported prepregnancy weight. The main statistical procedure used was the longitudinal mixed-effects model.

RESULTS

Mean postpartum weight retention at the end of the study was 3.1 kg. Single women aged > or = 30 y retained more weight than did younger single women or married women. The combined effect of breastfeeding duration and percentage of body fat at baseline was significant only for women with < 30% body fat. According to the model's prediction, when women who had 22% body fat and breastfed for 180 d were compared with those who had 22% body fat and breastfed for only 30 d, each month of breastfeeding contributed -0.44 kg to postpartum weight retention. When only the percentage of body fat was varied, the total effect was 3.0, 1.7, 1.2, and 0.04 kg in women with 18%, 25%, 28%, and 35% body fat, respectively.

CONCLUSIONS

These results support the hypothesis of an association between breastfeeding and postpartum weight retention and suggest that encouraging prolonged breastfeeding might contribute to decreases in postpartum weight retention.

Skinfold caliper and ultrasound assessments of change in the distribution of subcutaneous fat during adolescent pregnancy

OBJECTIVE

This study compares skinfold caliper and sonographic measurements of the amount and distribution of subcutaneous adipose tissue teenagers gain during pregnancy to test three hypotheses: (1) skinfold caliper and sonographic measurements of subcutaneous adiposity are highly correlated in pregnancy; (2) the extent to which the skinfold caliper heads compact the tissues increases during gestation; and (3) skinfold caliper measurements yield a smaller estimate of the amount of subcutaneous adipose tissue gained during gestation than do sonographic measurements.

METHODS

We studied 28 primiparous teenagers at 10.7+/-2.8 and 29.6+/-1.8 weeks gestation. At both study visits subcutaneous adipose tissue thickness was measured at six body sites, first by skinfold caliper and then by ultrasound. Taking the nearly compression-free sonographic measurements as the standard, we quantified the extent to which the skinfold caliper heads compacted the tissues at each measurement site by computing the percentage compression: (mean adipose tissue thickness by ultrasound-(0.5xmean adipose tissue thickness by caliper)/mean adipose tissue thickness by ultrasound)x100. Pearson correlations and paired t-tests were used to compare the skinfold caliper and sonographic measurements.

RESULTS

Hypothesis 1 was supported; the skinfold caliper and sonographic measurements were highly correlated at both study visits. Hypothesis 2 was not supported; between study visits caliper-related tissue compression decreased at measurement sites on the trunk and remained the same at measurement sites on the extremities. Hypothesis 3 was also refuted; the skinfold caliper-derived estimate of the amount of subcutaneous adipose tissue gained on the trunk exceeded the corresponding sonographic determination. As anticipated, the skinfold caliper measurements indicated that adipose tissue was stored more rapidly on the trunk than the extremities, but the opposite pattern emerged when the sonographic measurement technique was used.

CONCLUSIONS

The results of this study challenge the notion that pregnant women store adipose tissue preferentially on the trunk and suggest that pregnancy-related changes in the regional distribution of maternal body fat based on skinfold caliper measurements should be interpreted cautiously.

Exercise during the childbearing year

Many women wish to continue to pursue an active lifestyle during pregnancy, while the pregnancy itself may provide the motivation for other more sedentary women to begin an exercise program for the sake of improved health/fitness. Also, female competitive athletes, upon becoming pregnant, may wish to continue sports performance and require careful monitoring to assure maternal-fetal safety. This review is designed to assist the perinatal educator who is in the position to advise the pregnant patient on the risks and benefits of physical activity during the childbearing year and provide suggestions for developing individualized exercise programs.