Longitudinal changes in the relationship between body mass index and percent body fat in pregnancy

Association of maternal pre-pregnancy or first trimester body mass index with neurodevelopmental impairment or death in extremely low gestational age neonates

OBJECTIVE

To compare the rates of death or survival with severe neurodevelopmental impairment (sNDI) at 2 years among extremely preterm infants in relation to pre-pregnancy or first-trimester maternal body mass index (BMI).

METHODS

This retrospective cohort study included extremely preterm infants (gestational age 220/7-266/7 weeks). The study was conducted at National Institute of Child Health and Human Development Neonatal Research Network sites. The primary outcome was death or sNDI at 2 years.

RESULTS

Data on the primary outcome were available for 1208 children. Death or sNDI was not different among the three groups: 54.9% in normal, 56.1% in overweight, and 53.4% in obese group (p = 0.39). There was no significant difference in mortality, sNDI, moderate/severe cerebral palsy, Bayley Scales of Infant Development (BSID)-III cognitive composite score <70, BSID-III language composite score <70 in adjusted models.

CONCLUSION

Neurodevelopmental outcome was not significantly associated with maternal pre-pregnancy BMI among extreme preterm infants.

Disrupted Balance of the Oxidant-Antioxidant System in the Pathophysiology of Female Reproduction: Oxidative Stress and Adverse Pregnancy Outcomes

The significance of oxidative stress in the pathophysiology of male reproductive processes has been closely studied in the last two decades. Recently, it has become clear that oxidative stress can lead to numerous pathological conditions during female reproductive processes as well, contributing to the development of endometriosis, polycystic ovary syndrome and various forms of infertility. During pregnancy, physiological generation of reactive oxygen species (ROS) occurs in association with several developmental processes including oocyte maturation and implantation. An overproduction of ROS can lead to disturbances in fetal development and increases the risk for missed abortion, intrauterine growth restriction, pre-eclampsia, premature delivery and gestational diabetes. Our review focuses on the etiological role of the disrupted oxidant-antioxidant system during human gestation as it relates to adverse pregnancy outcomes.

Maternal Nutrition, Body Composition and Gestational Weight Gain on Low Birth Weight and Small for Gestational Age-A Cohort Study in an Indian Urban Slum

Maternal nutritional status and care during pregnancy are essential for adequate birth weight. In this prospective cohort study (N = 1061) in an urban slum, we investigated the association of maternal anthropometry, body composition, gestational weight gain and dietary intakes with low birthweight (LBW, <2.5 kg). About one-third of the women were short (<150 cm), 35% were underweight (<45 kg), 23% suffered from chronic energy deficiency (CED, BMI < 18.5 kg/m2) and another 30% were overweight/obese. The mean age and BMI were 23 years and 21.7 kg/m2, respectively, and haemoglobin was 10.73 g/dL. The mean birthweight (N = 605) was 2.81 ± 0.5 kg, and the average gestational age was 38 ± 2 weeks. About 15% of infants had LBW, and 48% were small for gestational age (SGA). Maternal body composition was assessed by skinfold thickness (SFT) in all trimesters. In the first trimester (N = 762), we found that mean fat-free mass (FFM), fat mass (FM) and body fat percentage (% BF) were 38.86 kg, 11.43 kg and 21.55%, respectively. Low birthweight was significantly associated with preterm deliveries (p < 0.001) and less fat free mass (p = 0.02) in the third trimester. Among other factors were age (p = 0.017), maternal anthropometry (height: p = 0.031; weight: p = 0.059) and fewer antenatal check-ups (p = 0.037). Small size (SGA) was consistently associated with maternal bodyweight at all trimesters (term I, p = 0.013, term II, p = 0.003 and term III, p < 0.001), fat mass in the third trimester (p < 0.001) and maternal height (p = 0.003).

Association between sleep disordered breathing in early pregnancy and glucose metabolism

STUDY OBJECTIVES

To examine the association between maternal sleep disordered breathing (SDB) and glucose metabolism in early gestation.

METHODS

Women with body mass index (BMI) ≥27 kg/m2 and singleton pregnancies underwent in-home sleep study (HSAT) and homeostatic model assessment (HOMA) in early pregnancy. Insulin resistance (HOMA-IR) and β-cell function (HOMA %B) were derived. Exclusion criteria included pregestational diabetes, use of continuous positive airway pressure and chronic steroid therapy. We performed linear regression analyses to evaluate the association between continuous measures of SDB (respiratory event index (REI), and oxygen desaturation index (ODI)) and glucose metabolism parameters (HOMA-IR and HOMA %B). Analyses were adjusted for a set of a priori selected variables which included gestational age, maternal age, BMI, ethnicity, race, and parity.

RESULTS

One hundred and ninety-two pregnant women with median (interquartile range) BMI of 35.14 (8.30) kg/m2 underwent HSAT and HOMA assessment at 11.14 (3) and 15.35 (4.14) gestational weeks, respectively. REI and ODI, as continuous values, were associated with HOMA-IR after adjusting for covariates. OSA (obstructive sleep apnea) diagnosis (REI > 5 events per hour) was not associated with HOMA-IR after adjusting for BMI (p ≥ 0.05). None of the parameters were associated with HOMA %B (p > 0.07).

CONCLUSIONS

SDB and insulin resistance are associated in early pregnancy, with a dose response association between respiratory event index severity and insulin resistance. Further studies are needed to establish if pregnant women with overweight and obesity may benefit from early SDB screening to improve glucose metabolic outcome. Clinical trials: NCT02412696, Positive Airway Pressure, Sleep Apnea, and the Placenta (PAP-SAP) https://clinicaltrials.gov/ct2/show/NCT02412696?term=Bourjeily&draw=2&rank=2 and NCT02917876, Predictors of De-novo Development of Obstructive Sleep Apnea in Pregnancy (Predictors) https://clinicaltrials.gov/ct2/show/NCT02917876?term=Bourjeily&draw=2&rank=1.

Self-reported (IFIS) versus measured physical fitness, and their associations to cardiometabolic risk factors in early pregnancy

Physical fitness is a strong marker of health, but objective fitness measurements are not always feasible. The International FItness Scale (IFIS) for self-reported fitness is a simple-to-use tool with demonstrated validity and reliability; however, validation in pregnancy needs to be confirmed. Also, its association with cardiometabolic health in pregnant women is unknown. Hence, we examined (1) the validity of the IFIS with objectively measured fitness, and (2) the associations of self-reported versus objectively measured cardiorespiratory fitness (CRF) and muscular strength with cardiometabolic risk factors in early pregnancy. Women (n = 303) from the HealthyMoms trial were measured at gestational week 14 for: CRF (6-min walk test); upper-body muscular strength (handgrip strength test); self-reported fitness (IFIS), body composition (air-displacement plethysmography); blood pressure and metabolic parameters (lipids, glucose, insulin). Higher self-reported fitness was associated with better measured fitness (ANOVA overall p < 0.01 for all fitness types), indicating the usefulness of the IFIS in pregnancy. Furthermore, higher self-reported overall fitness and CRF were associated with lower cardiometabolic risk scores (ANOVA p < 0.001), with similar results shown for measured CRF (ANOVA p < 0.001). The findings suggest that IFIS could be useful to stratify pregnant women in appropriate fitness levels on a population-based level where objective measurement is not possible.

Associations of body composition and physical fitness with gestational diabetes and cardiovascular health in pregnancy: Results from the HealthyMoms trial

The aim of this study was to examine associations of body composition (fat mass index, % fat mass, fat-free mass index, body mass index) and physical fitness (cardiorespiratory fitness and handgrip strength) with gestational diabetes and cardiovascular health in early pregnancy. This cross-sectional study utilized baseline data (n = 303) collected in early pregnancy from the HealthyMoms trial. Body composition was measured using air-displacement plethysmography, cardiorespiratory fitness was assessed by means of the 6-min walk test and handgrip strength using a dynamometer. Logistic regression was used to estimate odds ratios (ORs) for gestational diabetes as well as high (defined as 1 SD above the mean) blood pressure, homeostatic model assessment for insulin resistance (HOMA-IR), and metabolic syndrome score (MetS score) per 1 SD increase in body composition and fitness variables. Fat mass index, % fat mass and body mass index were all strongly associated with gestational diabetes (ORs: 1.72–2.14, P ≤ 0.003), HOMA-IR (ORs: 3.01–3.80, P < 0.001), blood pressure (ORs: 1.81–2.05, P < 0.001) and MetS score (ORs: 3.29–3.71, P < 0.001). Associations with fat-free mass index were considerably weaker (ORs: 1.26–1.82, P = 0.001–0.15) and were strongly attenuated after adjustments for fat mass index (ORs: 0.88–1.54, P = 0.039–0.68). Finally, greater cardiorespiratory fitness was associated with lower risk of high HOMA-IR and MetS score (ORs: 0.57–0.63, P  ≤ 0.004) although these associations were attenuated when accounting for fat mass index (ORs: 1.08-1.11, P ≥ 0.61). In conclusion, accurately measured fat mass index or % fat mass were strongly associated with gestational diabetes risk and markers of cardiovascular health although associations were not stronger than the corresponding ones for body mass index. Fat-free mass index had only weak associations with gestational diabetes and cardiovascular health which support that the focus during clinical care would be on excess fat mass and not fat-free mass.

National guidelines on nutrient reference values for the healthy adult population and for pregnant or lactating women are based on heterogeneous sources of evidence: review of guidelines

Many countries provide dietary guidelines for health practitioners and/or the general population. However, there is no general, international guideline serving as a template for national dietary guidelines, and there is little to no consensus regarding reference values for different nutrients. The present review compared 27 national dietary guidelines for healthy adults as well as for pregnant and/or breastfeeding women, and analysed their quality and the evidence behind their recommendations. The guidelines were evaluated for their quality using the instrument Agree II, and found to be heterogeneous (overall quality score 14%-100%) and often insufficient (quality score < 50%) due to missing information about their methodology and sources of evidence. We analysed the evidence (number of studies, study types and publication years) of reference values of a number of nutrients using the five guidelines that provided the highest scores in the Agree II assessment. The reference values varied among guidelines, were rarely based on up-to-date meta-analyses, and were often based on insufficiently reported evidence (22/27 guidelines with quality score < 50%). We recommend systematic reviews of high quality studies to formulate future guidelines, and to use guidelines on how to write guidelines.

In-hospital mortality and morbidity among extremely preterm infants in relation to maternal body mass index

OBJECTIVE

The objective of this paper is to compare in-hospital survival and survival without major morbidities in extremely preterm infants in relation to maternal body mass index (BMI).

METHODS

This retrospective cohort study included extremely preterm infants (gestational age 220/7-286/7 weeks). This study was conducted at National Institute of Child Health and Human Development Neonatal Research Network sites. Primary outcome was survival without any major morbidity.

RESULTS

Maternal BMI data were available for 2415 infants. Survival without any major morbidity was not different between groups: 30.8% in the underweight/normal, 28.1% in the overweight, and 28.5% in the obese (P = 0.65). However, survival was lower in the obese group (76.5%) compared with overweight group (83.2%) (P = 0.02). Each unit increase in maternal BMI was associated with decreased odds of infant survival (P < 0.01).

CONCLUSIONS

Survival without any major morbidity was not associated with maternal obesity. An increase in maternal prepregnancy BMI was associated with decreased odds of infant survival.

Contribution of Gestational Weight Gain on Maternal Glucose Metabolism in Women with GDM and Normal Glucose Tolerance

Context

Efforts to decrease the risk of developing metabolic complications of pregnancy such as gestational diabetes (GDM) through lifestyle intervention (decreasing excessive gestational weight gain (GWG)) during pregnancy have met with limited success.

Objective

The purpose of this study was to determine the relationship between the longitudinal changes in weight/body composition and insulin sensitivity and response in women with normal glucose tolerance (NGT) and those who developed GDM.

Design

We conducted a secondary analysis of a prospective cohort developed before conception and again at 34 to 36 weeks gestation. A total of 29 NGT and 17 GDM women were evaluated for longitudinal changes in insulin sensitivity/response using the hyperinsulinemic-euglycemic clamp and an IV-glucose tolerance test. Body composition was estimated using hydrodensitometry. Both absolute change (Δ) and relative change (%Δ) between these 2 time points were calculated. We performed simple and multiple linear regression analysis to assess the relationship between GWG and measures of glucose metabolism, ie, insulin sensitivity and response.

Results

Based on the primary study design there was no significant difference in clinical characteristics between women with NGT and those developing GDM. Prior to pregnancy, women who developed GDM had lower insulin sensitivity levels (P = 0.01) compared with NGT women. Absolute change and %Δ in insulin sensitivity/insulin response and body weight/body composition were not significantly different between NGT and GDM women. Changes in body weight contributed to only 9% of the Δ in insulin sensitivity both in women developing GDM and NGT women.

Conclusions

These data suggest that other factors—such as maternal pre-pregnancy insulin sensitivity and placental derived factors affecting insulin sensitivity—rather than maternal GWG account for the changes in glucose metabolism during human pregnancy.

Costs of reproduction and ageing in the human female

Evolutionary theories of ageing point to reproduction as a significant factor to consider when asking why ageing occurs and why there is inter-individual variation in its progression. Reproduction in human females is costly, in terms of energy, nutrients and metabolic adjustments. Thus, it is expected that women who experienced high reproductive effort resulting from multiple reproductive events will age faster. However, the evidence for long-term negative effects of reproduction is not conclusive. The lack of understanding of whether there are trade-offs between reproduction and ageing in women is partly due to methodological challenges. The costs of reproduction are often calculated based only on parity, while other elements contributing to these costs (e.g. breastfeeding, timing of reproduction) are neglected, which may significantly underestimate the total costs and obscure the all-important inter-individual variation in such costs. Costs must be evaluated in relation to individual characteristics, including developmental conditions, nutritional status and social support that a mother receives during reproduction. Furthermore, ageing and health must be assessed based on comprehensive markers rather than arbitrarily assembled variables. Finally, longitudinal rather than cross-sectional studies and new statistical approaches are needed to reveal how much of a decline in health and progressing ageing can actually be attributed to past reproductive processes. This article is part of the theme issue 'Evolution of the primate ageing process'.

Association of Overweight and Obesity Development Between Pregnancies With Stillbirth and Infant Mortality in a Cohort of Multiparous Women

OBJECTIVE

To identify the association of newly developed prepregnancy overweight and obesity with stillbirth and infant mortality.

METHODS

We studied subsequent pregnancies of mothers who were normal weight at fertilization of their first identified pregnancy, from a population-based cohort that linked birth registry with death records in Pennsylvania, 2003-2013. Women with newly developed prepregnancy overweight and obesity were defined as those whose body mass index (BMI) before second pregnancy was between 25 and 29.9 or 30 or higher, respectively. Our main outcomes of interest were stillbirth (intrauterine death at 20 weeks of gestation or greater), infant mortality (less than 365 days after birth), neonatal death (less than 28 days after birth) and postneonatal death (29-365 days after birth). Associations of both prepregnancy BMI categories and continuous BMI with each outcome were estimated by nonparametric targeted minimum loss-based estimation and inverse-probability weighted dose-response curves, respectively, adjusting for race-ethnicity, smoking, and other confounders (eg, age, education).

RESULTS

A cohort of 212,889 women were included for infant mortality analysis (192,941 women for stillbirth analysis). The crude rate of stillbirth and infant mortality in these final analytic cohorts were 3.3 per 1,000 pregnancies and 2.9 per 1,000 live births, respectively. Compared with women who stayed at a normal weight in their second pregnancies, those becoming overweight had 1.4 (95% CI 0.6-2.1) excess stillbirths per 1,000 pregnancies. Those becoming obese had 3.6 (95% CI 1.3-5.9) excess stillbirths per 1,000 pregnancies and 2.4 (95% CI 0.4-4.4) excess neonatal deaths per 1,000 live births. There was a dose-response relationship between prepregnancy BMI increases of more than 2 units and increased risk of stillbirth and infant mortality. In addition, BMI increases were associated with higher risks of infant mortality among women with shorter interpregnancy intervals (less than 18 months) compared with longer intervals.

CONCLUSION

Transitioning from normal weight to overweight or obese between pregnancies was associated with an increased risk of stillbirth and neonatal mortality.

Role of neurotrophins in pregnancy, delivery and postpartum

Neurotrophins (NTs) are a family of polypeptides whose functions have been extensively studied in the past two decades. In particular, Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF) play a major role in the development, nutrition and growth of the central and peripheral nervous system and in the pathogenesis of neurodegenerative, cardiometabolic and (auto)immune diseases. However, NGF and BDNF have subtle functions for follicular development, implantation, and placentation. This short narrative review summarizes the existing evidence, published between 2000 and 2019, about the role of NTs in many different conditions that might affect women during and after pregnancy such as preeclampsia, gestational diabetes, obesity, depression, anxiety, smoking and alcohol abuse. Literature suggests that the dysregulation of synthesis and release of NTs may lead to decisive effects on both maternal and fetal health. Some piece of evidences was found about a possible association between NGF/BDNF and breastfeeding. Additional studies on human models are necessary to further characterize the role of NTs in life-changing experiences like labor and delivery.

Maternal Overweight and Obesity and Risk of Congenital Heart Defects

BACKGROUND

Congenital heart defects are more frequent in offspring of mothers with overweight or obesity. However, associations between maternal overweight and obesity, and risks of complex and specific heart defects are not clear.

OBJECTIVES

This study sought to analyze associations between maternal overweight and obesity severity and rates of complex and specific heart defects.

METHODS

This was a population-based cohort study in Sweden, including 2,050,491 live singleton infants born between 1992 and 2012. Data on maternal and infant characteristics, and diagnoses of congenital heart defects were retrieved from nationwide registries. Maternal body mass index (BMI) was categorized as underweight (BMI <18.5 kg/m²), normal weight (BMI 18.5 to <25 kg/m²), overweight (BMI 25 to <30 kg/m²), obesity class I (BMI 30 to <35 kg/m²), class II (BMI 35 to <40 kg/m²), and class III (BMI ≥40 kg/m²). Outcomes included complex heart defects (tetralogy of Fallot, transposition of the great arteries, atrial septal defects [ASD], aortic arch defects, and single-ventricle heart) and subgroups of specific heart defects diagnosed up to 5 years of age. The authors calculated adjusted prevalence rate ratios (PRRs) with 95% confidence intervals.

RESULTS

A total of 28,628 (1.40%, N = 2,050,491) children had at least 1 congenital heart defect. PRRs of aortic arch defects increased with maternal obesity severity. Compared with offspring of normal weight mothers, PRRs of aortic arch defects and transposition of the great arteries were doubled in offspring of mothers with severe obesity. PRRs of ASD and persistent ductus arteriosus in term infants increased with maternal BMI.

CONCLUSIONS

PRRs of aortic branch defects, ASD, and persistent ductus arteriosus increase with maternal obesity severity.

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.

Poorer maternal diet quality and increased birth weight. J Matern Fetal Neonatal Med 2018;31:1613-1619. [PMID: 28514885 PMCID: PMC5694379 DOI: 10.1080/14767058.2017.1322949]

OBJECTIVE

Maternal diet and gestational weight gain (GWG) influence birth weight and infant adiposity, which are important predictors of lifetime health. To better understand these relationships, we studied associations between maternal diet and GWG, adiposity, and birth weight in a well characterized cohort of pregnant women.

STUDY DESIGN

Data were obtained from 41 term (>37 weeks), uncomplicated, singleton pregnancies according to pre-pregnancy BMI categories of normal (n = 11), overweight (n = 15), or obese (n = 15). Daily consumption of protein, fat, and carbohydrates and a Healthy Eating Index (HEI-2010) score were determined from 24 h food recall collections. Associations were modeled using multinomial logistic and linear regression.

RESULTS

Neither the third trimester maternal diet quality nor the macronutrient consumption was associated with GWG after adjusting for pre-pregnancy BMI, maternal age, and parity. A ten-point lower HEI-2010 score was associated with 200 g higher infant birth weight and a 1.0 cm longer length. However, maternal HEI-2010 and macronutrient composition were unrelated to infant percent body fat, ponderal index, or abdominal circumference.

CONCLUSIONS

Poorer third trimester maternal diet quality was associated with higher birth weight and longer length, but was unrelated to markers of infant adiposity. GWG was independent of third trimester maternal diet composition and quality.

Obesity and pregnancy: mechanisms of short term and long term adverse consequences for mother and child

Obesity is the most common medical condition in women of reproductive age. Obesity during pregnancy has short term and long term adverse consequences for both mother and child. Obesity causes problems with infertility, and in early gestation it causes spontaneous pregnancy loss and congenital anomalies. Metabolically, obese women have increased insulin resistance in early pregnancy, which becomes manifest clinically in late gestation as glucose intolerance and fetal overgrowth. At term, the risk of cesarean delivery and wound complications is increased. Postpartum, obese women have an increased risk of venous thromboembolism, depression, and difficulty with breast feeding. Because 50-60% of overweight or obese women gain more than recommended by Institute of Medicine gestational weight guidelines, postpartum weight retention increases future cardiometabolic risks and prepregnancy obesity in subsequent pregnancies. Neonates of obese women have increased body fat at birth, which increases the risk of childhood obesity. Although there is no unifying mechanism responsible for the adverse perinatal outcomes associated with maternal obesity, on the basis of the available data, increased prepregnancy maternal insulin resistance and accompanying hyperinsulinemia, inflammation, and oxidative stress seem to contribute to early placental and fetal dysfunction. We will review the pathophysiology underlying these data and try to shed light on the specific underlying mechanisms.

Cerebral blood flow regulation, exercise and pregnancy: why should we care?

Cerebral blood flow (CBF) regulation is an indicator of cerebrovascular health increasingly recognized as being influenced by physical activity. Although regular exercise is recommended during healthy pregnancy, the effects of exercise on CBF regulation during this critical period of important blood flow increase and redistribution remain incompletely understood. Moreover, only a few studies have evaluated the effects of human pregnancy on CBF regulation. The present work summarizes current knowledge on CBF regulation in humans at rest and during aerobic exercise in relation to healthy pregnancy. Important gaps in the literature are highlighted, emphasizing the need to conduct well-designed studies assessing cerebrovascular function before, during and after this crucial life period to evaluate the potential cerebrovascular risks and benefits of exercise during pregnancy.

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.

Weight change between successive pregnancies and risks of stillbirth and infant mortality: a nationwide cohort study

BACKGROUND

Maternal overweight and obesity are risk factors for stillbirth and infant mortality. Whether temporal changes in maternal weight affect these risks is not clear. We aimed to assess whether change of BMI between first and second pregnancies affects risks of stillbirth and infant mortality in the second-born offspring.

METHODS

In a Swedish population-based cohort of women who gave birth to their first and second child between Jan 1, 1992, and Dec 31, 2012, we investigated associations between change in maternal body-mass index (BMI) during early pregnancy from first to second pregnancies and risks of stillbirth and neonatal, postneonatal, and infant mortality after the second pregnancy. Relative risks (RRs) for each outcome according to BMI change categories were calculated with binomial regression.

FINDINGS

Complete information was available for 456,711 (77.7%) of 587,710 women who had their first and second single births in the study period. Compared with women with a stable BMI (change between -1 kg/m(2) and <1 kg/m(2)) between pregnancies, the adjusted RRs for women who gained at least 4 BMI units between pregnancies were 1.55 (95% CI 1.23-1.96) for stillbirth and 1.29 (1.00-1.67) for infant mortality. Stillbirth risks increased linearly with increased BMI gain. Risks of infant mortality in second pregnancy only increased with BMI gain in women with healthy BMI (<25 kg/m(2)) during first pregnancy; the adjusted RR for healthy weight women who gained 2 to less than 4 BMI units was 1.27 (1.01-1.59) and for those who gained 4 BMI units or more the adjusted RR was 1.60 (1.16-2.22). In overweight women (BMI ≥25 kg/m(2)), weight loss before pregnancy reduced risk of neonatal mortality.

INTERPRETATION

Our findings emphasise the need to prevent weight gain before pregnancy in healthy and overweight women and that weight loss should be promoted in overweight women.

FUNDING

Swedish Research Council for Health, Working Life and Welfare, and Karolinska Institutet.

Glucose Homeostasis Variables in Pregnancy versus Maternal and Infant Body Composition

Intrauterine factors influence infant size and body composition but the mechanisms involved are to a large extent unknown. We studied relationships between the body composition of pregnant women and variables related to their glucose homeostasis, i.e., glucose, HOMA-IR (homeostasis model assessment-insulin resistance), hemoglobin A1c and IGFBP-1 (insulin-like growth factor binding protein-1), and related these variables to the body composition of their infants. Body composition of 209 women in gestational week 32 and of their healthy, singleton and full-term one-week-old infants was measured using air displacement plethysmography. Glucose homeostasis variables were assessed in gestational week 32. HOMA-IR was positively related to fat mass index and fat mass (r2 = 0.32, p < 0.001) of the women. Maternal glucose and HOMA-IR values were positively (p ≤ 0.006) associated, while IGFBP-1 was negatively (p = 0.001) associated, with infant fat mass. HOMA-IR was positively associated with fat mass of daughters (p < 0.001), but not of sons (p = 0.65) (Sex-interaction: p = 0.042). In conclusion, glucose homeostasis variables of pregnant women are related to their own body composition and to that of their infants. The results suggest that a previously identified relationship between fat mass of mothers and daughters is mediated by maternal insulin resistance.

Maternal obesity and metabolic risk to the offspring: why lifestyle interventions may have not achieved the desired outcomes

Obesity during pregnancy is associated with an increased risk of short- and long-term metabolic dysfunction in the mother and her offspring. Both higher maternal pregravid body mass index (kg m(-2)) and excessive gestational weight gain (GWG) have been associated with adverse pregnancy outcomes such as gestational diabetes, preeclampsia and fetal adiposity. Multiple lifestyle intervention trials consisting of weight management using various diets, increased physical activity and behavioral modification techniques have been employed to avoid excessive GWG and improve perinatal outcomes. These randomized controlled trials (RCTs) have achieved modest success in decreasing excessive GWG, although the decrease in GWG was often not within the current Institute of Medicine guidelines. RCTs have generally not had any success with decreasing the risk of maternal gestational diabetes (GDM), preeclampsia or excessive fetal growth often referred to as macrosomia. Although the lack of success for these trials has been attributed to lack of statistical power and poor compliance with study protocols, our own research suggests that maternal pregravid and early pregnancy metabolic condition programs early placenta function and gene expression. These alterations in maternal/placental function occur in the first trimester of pregnancy prior to when most intervention trials are initiated. For example, maternal accrural of adipose tissue relies on prior activation of genes controlling lipogenesis and low-grade inflammation in early pregnancy. These metabolic alterations occur prior to any changes in maternal phenotype. Therefore, trials of lifestyle interventions before pregnancy are needed to demonstrate the safety and efficacy for both the mother and her offspring.

Maternal overweight and obesity in early pregnancy and risk of infant mortality: a population based cohort study in Sweden

OBJECTIVE

To investigate associations between maternal overweight and obesity and infant mortality outcomes, including cause-specific mortality.

DESIGN

Population based cohort study.

SETTING AND PARTICIPANTS

1,857,822 live single births in Sweden 1992-2010.

MAIN OUTCOME MEASURES

Associations between maternal body mass index (BMI) in early pregnancy and risks of infant, neonatal, and postneonatal mortality, overall and stratified by gestational length and by causes of infant death. Odds ratios were adjusted for maternal age, parity, smoking, education, height, country of birth, and year of delivery.

RESULTS

Infant mortality rates increased from 2.4/1000 among normal weight women (BMI 18.5-24.9) to 5.8/1000 among women with obesity grade 3 (BMI ≥ 40.0). Compared with normal weight, overweight (BMI 25.0-29.9) and obesity grade 1 (BMI 30.0-34.9) were associated with modestly increased risks of infant mortality (adjusted odds ratios 1.25 (95% confidence interval 1.16 to 1.35) and 1.37 (1.22 to 1.53), respectively), and obesity grade 2 (BMI 35.0-39.9) and grade 3 were associated with more than doubled risks (adjusted odds ratios 2.11 (1.79 to 2.49) and 2.44 (1.88 to 3.17)). In analyses stratified by preterm and term births, maternal BMI was related to risks of infant mortality primarily in term births (≥ 37 weeks), where risks of deaths due to birth asphyxia and other neonatal morbidities increased with maternal overweight and obesity. Obesity grade 2-3 was also associated with increased infant mortality due to congenital anomalies and sudden infant death syndrome.

CONCLUSIONS

Maternal overweight and obesity are associated with increased risks of infant mortality due to increased mortality risk in term births and an increased prevalence of preterm births. Maternal overweight and obesity may be an important preventable risk factor for infant mortality in many countries.

The concurrent validity between leptin, BMI and skin folds during pregnancy and the year after

Background:

From a public health perspective it is important to know which of the currently used methods to estimate changes in maternal body fat during pregnancy and the year thereafter is the most adequate.

Objectives:

To evaluate the concurrent validity between leptin and surrogates of fat measures: body mass index (BMI) and the sum of four skin folds.

Design:

Data from the New Life(style) intervention study were analysed as a cohort study.

Setting:

Midwife practices in The Netherlands.

Population:

Healthy pregnant nulliparous women.

Methods:

Anthropometric measurements were done and blood was collected at 15, 25 and 35 weeks of pregnancy and at 6, 26 and 52 weeks after delivery. Data were used if at least 4 out of the 6 measurements were available, leaving 87 women in the analyses. Spearman's correlation coefficients between leptin and BMI and between leptin and the sum of skin folds were calculated for each time point and for the changes between the time points.

Results:

Correlations between leptin and BMI varied from 0.69 to 0.81. Correlations between leptin and the sum of skin folds were comparable, varying between 0.65 and 0.81.

Correlations between changes in leptin and changes in BMI and the sum of skin folds, respectively, were much lower compared with cross-sectional correlations.

Conclusion:

Because of the high correlation among the three methods and because of the overlapping intervals, all methods seem to be equally adequate to estimate changes in maternal body fat during pregnancy and the year thereafter.

Assessment and prediction of thoracic gas volume in pregnant women: an evaluation in relation to body composition assessment using air displacement plethysmography

Assessment of body fat (BF) in pregnant women is important when investigating the relationship between maternal nutrition and offspring health. Convenient and accurate body composition methods applicable during pregnancy are therefore needed. Air displacement plethysmography, as applied in Bod Pod, represents such a method since it can assess body volume (BV) which, in combination with body weight, can be used to calculate body density and body composition. However, BV must be corrected for the thoracic gas volume (TGV) of the subject. In non-pregnant women, TGV may be predicted using equations, based on height and age. It is unknown, however, whether these equations are valid during pregnancy. Thus, we measured the TGV of women in gestational week 32 (n 27) by means of plethysmography and predicted their TGV using equations established for non-pregnant women. Body weight and BV of the women was measured using Bod Pod. Predicted TGV was significantly (P = 0·033) higher than measured TGV by 6 % on average. Calculations in hypothetical women showed that this overestimation tended to be more pronounced in women with small TGV than in women with large TGV. The overestimation of TGV resulted in a small but significant (P = 0·043) overestimation of BF, equivalent to only 0·5 % BF, on average. A Bland-Altman analysis showed that the limits of agreement were narrow (from -1·9 to 2·9 % BF). Thus, although predicted TGV was biased and too high, the effect on BF was marginal and probably unimportant in many situations.

Bioimpedance in pregnant women with preeclampsia

To analyze the direct (resistance and reactance) and indirect (intra and extracellular total body water) BIA parameters in preeclamptic women, 51 healthy pregnant women and 65 preeclamptic women were submmited to bioelectric impedance on the third trimester of gestation. The significance value adopted was 5%. Preeclamptic women showed lower values for R (448 Ω vs. 542 Ω), Rc (40 Ω vs. 53 Ω) and ICW (49.45% vs. 51%) when compared to control group. They also showed higher values for TBW (49% vs. 47%), TBWcor (41.6% vs. 34%) and ECW (50% vs. 47%). Bioelectric impedance allowed differentiating preeclamptic women from health pregnant women, indicating that preeclampsia changes body compartments during pregnancy. This method can help understand the mechanisms involved in preeclampsia and to be a prediction away of preeclampsia.

Energy requirements during pregnancy and lactation

Objective

To estimate the energy requirements of pregnant and lactating women consistent with optimal pregnancy outcome and adequate milk production.

Design

Total energy cost of pregnancy was estimated using the factorial approach from pregnancy-induced increments in basal metabolic rate measured by respiratory calorimetry or from increments in total energy expenditure measured by the doubly labelled water method, plus energy deposition attributed to protein and fat accretion during pregnancy.

Setting

Database on changes in basal metabolic rate and total energy expenditure during pregnancy, and increments in protein based on measurements of total body potassium, and fat derived from multi-compartment body composition models was compiled. Energy requirements during lactation were derived from rates of milk production, energy density of human milk, and energy mobilisation from tissues.

Subjects

Healthy pregnant and lactating women.

Results

The estimated total cost of pregnancy for women with a mean gestational weight gain of 12.0 kg, was 321 or 325 MJ, distributed as 375, 1200, 1950 kJ day-1, for the first, second and third trimesters, respectively. For exclusive breastfeeding, the energy cost of lactation was 2.62 MJ day-1 based on a mean milk production of 749 g day-1, energy density of milk of 2.8 kJ g-1, and energetic efficiency of 0.80. In well-nourished women, this may be subsidised by energy mobilisation from tissues on the order of 0.72 MJ day-1, resulting in a net increment of 1.9 MJ day-1 over non-pregnant, non-lactating energy requirements.

Conclusions

Recommendations for energy intake of pregnant and lactating women should be updated based on recently available data.

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.

Energy requirements during pregnancy based on total energy expenditure and energy deposition

BACKGROUND

Energy requirements during pregnancy remain controversial because of uncertainties regarding maternal fat deposition and reductions in physical activity.

OBJECTIVE

This study was designed to estimate the energy requirements of healthy underweight, normal-weight, and overweight pregnant women and to explore energetic adaptations to pregnancy.

DESIGN

The energy requirements of 63 women [17 with a low body mass index (BMI; in kg/m(2)), 34 with a normal BMI, and 12 with a high BMI] were estimated at 0, 9, 22, and 36 wk of pregnancy and at 27 wk postpartum. Basal metabolic rate (BMR) was measured by calorimetry, total energy expenditure (TEE) by doubly labeled water, and activity energy expenditure (AEE) as TEE - BMR. Energy deposition was calculated from changes in body protein and fat. Energy requirements equaled the sum of TEE and energy deposition.

RESULTS

BMR increased gradually throughout pregnancy at a mean (+/-SD) rate of 10.7 +/- 5.4 kcal/gestational week, whereas TEE increased by 5.2 +/- 12.8 kcal/gestational week, which indicated a slight decrease in AEE. Energy costs of pregnancy depended on BMI group. Although total protein deposition did not differ significantly by BMI group (mean for the 3 groups: 611 g protein), FM deposition did (5.3, 4.6, and 8.4 kg FM in the low-, normal-, and high-BMI groups; P = 0.02). Thus, energy costs differed significantly by BMI group (P = 0.02). In the normal-BMI group, energy requirements increased negligibly in the first trimester, by 350 kcal/d in the second trimester, and by 500 kcal/d in the third trimester.

CONCLUSION

Extra energy intake is required by healthy pregnant women to support adequate gestational weight gain and increases in BMR, which are not totally offset by reductions in AEE.

Relation between maternal body composition and birth weight

In order to establish the relationship between maternal body composition indicators (fat-free mass, fat mass, total body water) and birth weight, a cross-sectional study was designed, based on 196 pairs of mothers and live singleton newborns with gestational age of 37 weeks or more. Immediately after delivery, the mothers were interviewed to obtain information about different birth weight predictors. An analysis of maternal body composition through bioelectric impedance was held. Multiple linear regression was used to measure the effect of each variable on birth weight. The birth weight mean was 3,251 +/- 514 g. Maternal height was 160.44 +/- 6.3 cm, total net weight gain was 5.85 +/- 5.15 kg, fat mass consisted of 15.84 +/- 6.72 kg, and fat-free mass was 50.42 +/- 7.65 kg; total body water was 34.82 +/- 5.61 liters. The model which included total body water and all predictors found to be associated with birth weight in the bivariate analysis (maternal age, gestational age, gender, placenta weight, and placenta weight squared) was found to be the best in explaining the variability of birth weight (R(2) = 45.26%). Fat mass was an important predictor only in the subgroup of women within the low tertile of body mass index. In conclusion, fat-free mass and total body water explained a major proportion of the variability of birth weight in comparison with the mother's weight gain during the pregnancy period, which has already been considered an important predictor of birth weight.

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.

The influence of obesity and gestational diabetes mellitus on accretion and the distribution of adipose tissue in pregnancy

OBJECTIVE

The purpose of this study was to evaluate the effect of pregravid obesity and gestational diabetes mellitus (GDM) on the longitudinal accretion and distribution of adipose tissue in pregnancy.

STUDY DESIGN

Women with normal glucose tolerance and GDM were evaluated before conception, early (12-14 weeks) and late (33-36 weeks) in gestation. Fat mass, lean body mass, and percent body fat were assessed longitudinally with hydrodensitometry. Serial biceps, triceps, subscapular, iliac, costal, mid thigh, and lower thigh skinfold measurements quantified the changes in fat mass distribution. Pregravid obesity was defined as >25% body fat.

RESULTS

Subjects included 19 patients with GDM (5 lean women, 14 obese women), and 33 patients with normal glucose tolerance (controls; 12 lean women, 21 obese women). GDM and control subjects were similar in pregravid percent body fat (29.6% vs 27.9%, P=.47) and fat mass (20.8 kg vs 18.2 kg, P=.37). Values for subjects with GDM and controls were also similar in terms of percent body fat, fat mass, and weight gained (change in percent body fat, -0.7% vs 1.9% [P=.07]; change in fat mass, 3.8 kg vs 5.0 kg [P=.08]; change in weight, 12.0 kg vs 13.2 kg [P=.35]). Lean subjects gained more percent body fat compared with obese subjects (change in percent body fat, 3.3% vs 0.1% [P=.004]) but gained similar amounts of fat mass (change in fat mass, 4.7 kg vs 4.2 kg [P=.58]), lean body mass (7.6 kg vs 8.8 kg [P=.18]), and weight (change in weight, 12.3kg vs 13.0 kg [P=.61]) The distribution of adipose tissue that was accumulated as estimated with skinfold measurements was similar between patients with GDM and glucose tolerance (P>.05 for all changes in skinfolds), but significantly different between lean and obese patients (P<.05 for all changes in skinfolds). Lean women gained a predominance of adipose tissue peripherally over that in obese women.

CONCLUSION

Lean women accrue significantly more fat mass than obese women, regardless of glucose tolerance. Pregestational obesity rather than GDM influences the distribution of adipose accretion.

Postpartum care of the woman with diabetes

The postpartum period in women with diabetes or GDM allows both the physician and mother to relax from the intensive medical and obstetric management that has permitted, in most cases, a successful and joyous outcome. The role of the physician, however, must switch to a proactive and preventive mode to formulate a reproductive health plan for women with diabetes and GDM. The plan should be individualized to address glycemic management and surveillance, nutritional management, contraception prescription, future pregnancy planning, and lifestyle changes. Essential to the development of a reproductive health plan is the active participation of the patient, who through education gains an understanding of the far-reaching effects her active participation will have on her subsequent health and possibly on that of her future children.

Interaction of body weight and ethnicity on risk of gestational diabetes mellitus

BACKGROUND

The James Bay Cree of Canada have one of the highest recorded rates of gestational diabetes mellitus (GDM) among aboriginal people worldwide; the reasons for this elevated risk remain to be documented.

OBJECTIVE

Our objective was to compare predictors and risk of GDM between the James Bay Cree and non-Native Canadians.

DESIGN

Risk for GDM was compared between Cree and non-Native women by 1) adjusting statistically for differences in age, parity, pregravid weight, and smoking status (n = 402 Cree, 7718 non-Natives), and 2) matching Cree women with non-Native women for age and pregravid weight (n = 394 Cree, 788 non-Natives). Dietary and physical activity information was available for a subset of Cree women (n = 152).

RESULTS

Age and pregravid weight were independent predictors of GDM in both Cree and non-Native women. After these predictors were controlled for, normal-weight (</=77 kg) Cree women were not at increased risk of GDM (OR: 1.42; 95% CI: 0.67, 2.71) but overweight Cree women had a higher risk than did overweight non-Native women (OR: 2.25; 95% CI: 1.32, 3.80).

CONCLUSIONS

Overweight Cree women are at increased risk of GDM. Given the high prevalence of pregravid overweight among the Cree, the burden of GDM is higher than among non-Native Canadians.