Pre-gravid physical activity and reduced risk of glucose intolerance in pregnancy: the role of insulin sensitivity

Physical activity during pregnancy and adverse birth outcome: a prospective cohort study in China

Objectives The relationship between prenatal physical activity (PA) and adverse birth outcomes is still inconclusive. We aimed to investigate the association between PA during pregnancy and adverse birth outcomes by using data from the Guangxi Zhuang birth cohort (GZBC) in China.Study Design A total of 11,292 mother-infant pairs were included from GZBC in China. The information on PA status, intensity, adequacy, and volume and birth outcomes were collected. Multivariable linear and logistic regression models were applied to analyze the effects of PA during pregnancy on birth weight z-scores (BW z-scores) and gestational age and risk of small-for-gestational age (SGA) and preterm birth (PTB), respectively. Cubic spline analysis was conducted to detect a nonlinear dose-response of total weekly activity metabolic equivalents (MET) and birth outcomes.Results Compared to no regular PA during pregnancy, moderate and high-intensity PA (MVPA) was associated with increase BW z-scores (β = 0.08, 95%CI: 0.002, 0.15, p = .044) and associated with a marginal significant decrease in risk of PTB (OR = 0.73, 95%CI: 0.51, 1.05, p = .093). However, PA had no relationship with gestational age and risk of SGA, and Nonlinear relationships were not observed between total weekly activity MET and risk of SGA and PTB.Conclusion These finding shows that PA during pregnancy may increase the BW z-score and reduce risk of PTB, supporting the guidelines that pregnant women should be encouraged to engage in appropriate physical activity during pregnancy in China.

Simple method for identification of women at risk of gestational diabetes mellitus in Arusha urban, Tanzania

BACKGROUND

Screening for gestational diabetes mellitus in Tanzania is challenged by limited resources. Therefore, this study aimed to develop a simple method for identification of women at risk of gestational diabetes mellitus in Arusha urban, Tanzania.

METHODS

This study used data from a cross sectional study, that was conducted between March and December 2018 in Arusha District involving 468 pregnant women who were not known to have diabetes before pregnancy. Urine glucose was tested using urine multistics and blood glucose levels by Gluco-Plus™ and diagnosed in accordance with the World Health Organization's criteria. Anthropometrics were measured using standard procedures and maternal characteristics were collected through face-to-face interviews using a questionnaire with structured questions. Univariate analysis assessed individual variables association with gestational diabetes mellitus where variables with p-value of < 0.05 were included in multivariable analysis and predictors with p-value < 0.1 remained in the final model. Each variable was scored based on its estimated coefficients and risk scores were calculated by multiplying the corresponding coefficients by ten to get integers. The model's performance was assessed using c-statistic. Data were analyzed using Statistical Package for Social Science™.

RESULTS

The risk score included body fat ≥ 38%, delivery to macrosomic babies, mid-upper arm circumference ≥ 28 cm, and family history of type 2 diabetes mellitus. The score correctly identified 98% of women with gestational diabetes with an area under the receiver operating characteristic curve of 0.97 (95% CI 0.96-0.99, p < 0.001), sensitivity of 0.98, and specificity of 0.46.

CONCLUSION

The developed screening tool is highly sensitive and correctly differentiates women with and without gestational diabetes mellitus in a Tanzanian sub-population.

Enablers and barriers to women's lifestyle behavior change during the preconception period: A systematic review

Healthy lifestyle behaviors during the preconception period are important to optimize maternal and child outcomes, including weight. However, the majority of women do not have optimal preconception lifestyle behaviors. This systematic review explored enablers and barriers to women's preconception lifestyle behaviors using the Capability, Opportunity, Motivation, Behaviour (COM-B) model and Theoretical Domains Framework (TDF). Preconception was defined as the time before conception, capturing planned and unplanned pregnancies. Medline Complete, EMBASE, PsycINFO, and CINAHL were searched for peer-reviewed, quantitative and qualitative primary studies (English, 2006-2020) that explored enablers and barriers to lifestyle behaviors (diet, physical activity, smoking, alcohol use, supplement intake). Forty-two studies (of 3406) were included, assessing supplement use (n = 37), diet (n = 10), smoking (n = 10), alcohol use (n = 8), and physical activity (n = 5). All three COM-B components were identified only for diet and supplement use. Of the 14 TDF domains, 7 were identified: knowledge, beliefs about capabilities, beliefs about consequences, goals, intentions, social support, and environmental context and resources. The presence/absence of knowledge on healthy behaviors was the most commonly assessed enabler/barrier. Future studies should explore a wider range of factors influencing preconception women's capability, opportunity, and motivation to modify their lifestyle behaviors.

Do obesity and low levels of physical activity increase the risk for developing type 2 diabetes mellitus among women with prior gestational diabetes in rural China?

Moderate-to-vigorous intensity physical activity (MVPA) and obesity play important roles in the development of type 2 diabetes mellitus (T2DM) among women with prior gestational diabetes mellitus (GDM). Yet, how MVPA affects the risk of developing T2DM among women with prior GDM across the different categories of obesity indicators is unclear. This study aimed to describe the levels of postpartum abnormal glucose tolerance (AGT), obesity indicators (body mass index [BMI] and waist circumference [WC]), and MVPA and to explore the independent effect and joint effect of MVPA and obesity indicators (BMI and WC) on the risk for developing AGT among women with prior GDM in rural China. A total of 425 women with prior GDM were recruited from two county-level hospitals in Western and Eastern Hunan, China. Data were collected with self-reported measurements on sociodemographics and clinical factors as well as postpartum weight-related behaviors (physical activity and dietary intake). The 75-g oral glucose tolerance test, weight, height, and WC were measured on site. Binary logistic regression models and multiplitive interaction models were used to explore the independent and joint associations of BMI and MVPA as well as WC and MVPA on AGT, respectively. One-fifth (20.9%) of the sample women had AGT. The obesity indicators were significantly associated with an increased risk of postpartum AGT, but MVPA was not. In joint effect analyses, larger WC and insufficient MVPA were not significantly associated with increased risk of AGT compared with normal WC and sufficient MVPA (mutually adjusted odds ratio [OR], 1.43; 95% confidence interval [CI], 0.46-4.43; p > .05). In joint effect analyses of MVPA and BMI, the mutually adjusted OR for developing AGT in women who were obese and had insufficient MVPA was 4.49 (95% CI, 1.35-14.92; p < .05) compared with normal weight and sufficient MVPA. Adequate weight management and increased MVPA are warranted for Chinese women with prior GDM to prevent T2DM.

Review of general suggestions on physical activity to prevent and treat gestational and pre-existing diabetes during pregnancy and in postpartum

The aim of this review is to provide general suggestions on physical activity (PA) in pre-gestational and gestational diabetes mellitus (GDM) and encourage women to take part in safe and effective activities throughout pregnancy, in the absence of other contraindications. PA before and during pregnancy and in postpartum has many positive effects on the mother, as it could reduce the risk of GDM, excessive weight gain and lower back pain and also prevents, in the postpartum, diabetes mellitus. It may also reduce the duration of labour and complications at childbirth, fatigue, stress, anxiety and depression, thereby leading to an improved sense of wellbeing. Clinically, it is thought to help prevent preeclampsia and premature birth even though RCTs provide conflicting evidence with regard to the prevention of GDM. The main reason for this rests on the fact that the majority of clinical trials have not been able to replicate the preventive effect of PA on the onset of GDM, such as the different adherence of the patient to PA. Herein, we survey the literature regarding exercise and PA on GDM prevention and treatment as well as on clinical outcomes in pre-GDM in pregnancy. On the basis of the current literature, we also present a series of general recommendations and suggestions on PA and exercise training in pregnancy among both diabetic patients and those at risk for GDM.

Physical activity and epigenetic biomarkers in maternal blood during pregnancy

AIM

Investigate associations of leisure time physical activity (LTPA) with DNA methylation and miRNAs during pregnancy. Patients & methods: LTPA, candidate DNA methylation and circulating miRNAs were measured (average 15 weeks gestation) in pregnant women (n = 92).

RESULTS

Each additional hour of prepregnancy LTPA duration was associated with hypermethylation in C1orf212 (β = 0.137, 95% CI: 0.004-0.270) and higher circulating miR-146b-5p (β = 0.084, 95% CI: 0.017-0.151). Each additional metabolic equivalent hour of early-pregnancy LTPA energy expenditure was associated with higher circulating miR-21-3p (β = 0.431, 95% CI: 0.089-0.772) in women carrying female offspring, and lower circulating miR-146b-5p (β = -0.285, 95% CI: -0.528 to -0.043) and miR-517-5p (β = -0.406, 95% CI: -0.736 to -0.076) in women carrying male offspring.

CONCLUSION

Our findings suggest that LTPA may influence maternal epigenetic biomarkers, possibly in an offspring sex-specific manner.

Ethnic Disparities in Gestational Diabetes

PURPOSE OF REVIEW

Ethnicity has long been described as a major risk factor for the development of gestational diabetes mellitus (GDM), and it is widely recognised that women from ethnicities other than Europids are at higher risk of developing GDM. There are also described differences between ethnicities in key GDM pregnancy outcomes. This review describes some of the factors that relate to the ethnic disparities in GDM.

RECENT FINDINGS

The global prevalence of GDM has been steadily increasing and estimated to be 16.2% from the International Diabetes Federation extrapolation. Reported prevalence rates may understate the true prevalence, due to factors of access and attitudes to GDM diagnosis and screening in low resource settings for foreign-born women and indigenous populations. Other factors may relate to genes associated with specific ethnicities, obesity, body composition and gestational weight gain. Various factors such as access to screening, body composition, genetics and gestational weight gain may result in ethnic disparities in the prevalence and outcomes of GDM.

Associations of physical activity and sedentary behavior during pregnancy with gestational diabetes mellitus among Asian women in Singapore

BACKGROUND

Few studies have investigated physical activity (PA) and sedentary behavior (SB) in relation to fasting (FG) and 2-h postprandial plasma glucose (2hPG) levels and gestational diabetes mellitus (GDM); we investigated these associations among Asian pregnant women.

METHODS

As part of the Growing Up in Singapore Towards healthy Outcomes cohort study, PA and SB (sitting and television times) were assessed by interviewer-administered questionnaire. During 75 g oral glucose tolerance tests at 26-28 weeks' gestation we measured FG, 2hPG levels and GDM (FG ≥ 7.0 mmol/L and/or 2hPG ≥ 7.8 mmol/L). Associations were analysed by multiple linear and logistic regression.

RESULTS

Among the 1083 women studied, 18.6% had GDM. SB was not associated with FG, 2hPG and GDM. Higher categories of PA were associated with lower 2hPG and a lower likelihood of GDM (p-trend < 0.05), but not with FG levels. Compared to insufficiently active women, highly active women had lower 2hPG levels [β (95% CI): -0.32 (-0.59, -0.05), p = 0.020) and were less likely to have GDM [OR: 0.56 (0.32-0.98), p = 0.040]. Stratified analysis revealed no associations among under/normal-weight women, but significant associations among overweight/obese women; in those with BMI ≥23 kg/m2, sufficiently active and highly active women were less likely to have GDM [OR: 0.52, (0.29-0.93), p = 0.028, and OR: 0.34, (0.15-0.77), p = 0.010, respectively].

CONCLUSION

Higher PA was associated with lower 2hPG levels and a lower prevalence of GDM, particularly in overweight/obese women. Further studies are warranted to confirm these findings, and to examine the effectiveness of PA promotion strategies for the prevention of gestational hyperglycemia.

Exercise during pregnancy and its impact on mothers and offspring in humans and mice

Exercise during pregnancy has beneficial effects on maternal and offspring’s health in humans and mice. The underlying mechanisms remain unclear. This comparative study aimed to determine the long-term effects of an exercise program on metabolism, weight gain, body composition and changes in hormones [insulin, leptin, brain-derived neurotrophic factor (BDNF)]. Pregnant women (n=34) and mouse dams (n=44) were subjected to an exercise program compared with matched controls (period I). Follow-up in the offspring was performed over 6 months in humans, corresponding to postnatal day (P) 21 in mice (period II). Half of the mouse offspring was challenged with a high-fat diet (HFD) for 6 weeks between P70 and P112 (period III). In period I, exercise during pregnancy led to 6% lower fat content, 40% lower leptin levels and an increase of 50% BDNF levels in humans compared with controls, which was not observed in mice. After period II in humans and mice, offspring body weight did not differ from that of the controls. Further differences were observed in period III. Offspring of exercising mouse dams had significantly lower fat mass and leptin levels compared with controls. In addition, at P112, BDNF levels in offspring were significantly higher from exercising mothers while this effect was completely blunted by HFD feeding. In this study, we found comparable effects on maternal and offspring’s weight gain in humans and mice but different effects in insulin, leptin and BDNF. The long-term potential protective effects of exercise on biomarkers should be examined in human studies.

Physical activity and the risk of preterm birth: a systematic review and meta-analysis of epidemiological studies

BACKGROUND

Physical activity has been inconsistently associated with risk of preterm birth, and the strength of the association and the shape of the dose-response relationship needs clarification.

OBJECTIVES

To conduct a systematic review and dose-response meta-analysis to clarify the association between physical activity and risk of preterm birth.

SEARCH STRATEGY

PubMed, Embase and Ovid databases were searched for relevant studies up to 9 February 2017.

SELECTION CRITERIA

Studies with a prospective cohort, case-cohort, nested case-control or randomized study design were included.

DATA COLLECTION AND ANALYSIS

Data were extracted by one reviewer and checked for accuracy by a second reviewer. Summary relative risks (RRs) were estimated using a random effects model.

MAIN RESULTS

Forty-one studies (43 publications) including 20 randomized trials and 21 cohort studies were included. The summary RR for high versus low activity was 0.87 [95% confidence interval (CI): 0.70-1.06, I² = 17%, n = 5] for physical activity before pregnancy, and it was 0.86 (95% CI: 0.78-0.95, I² = 0%, n = 30) for early pregnancy physical activity. The summary RR for a 3 hours per week increment in leisure-time activity was 0.90 (95% CI: 0.85-0.95, I² = 0%, n = 5). There was evidence of a nonlinear association between physical activity and preterm birth, P_nonlinearity < 0.0001, with the lowest risk observed at 2-4 hours per week of activity.

CONCLUSION

This meta-analysis suggests that higher leisure-time activity is associated with reduced risk of preterm birth. Further randomized controlled trials with sufficient frequency and duration of activity to reduce the risk and with larger sample sizes are needed to conclusively demonstrate an association.

TWEETABLE ABSTRACT

Physically active compared with inactive women have an 10-14% reduction in the risk of preterm birth.

Opportunities for probiotics and polyunsaturated fatty acids to improve metabolic health of overweight pregnant women

Overweight during pregnancy predisposes both the mother and foetus to health complications. Maternal complications include gestational diabetes, obstetric problems and type 2 diabetes later in life. Complications for the offspring are not only restricted to the foetal period or birth, such as prematurity and foetal macrosomia, but may also have long-term metabolic health implications through the mechanism of early nutrition programming. One of the key metabolic components characterising overweight in the non-pregnant state is low-grade inflammation manifested by elevated levels of circulatory pro-inflammatory cytokines. In pregnancy, in addition to adipose tissue and placenta, inflammatory response may originate from the gut. The extent to which overweight induces metabolic maladaptation during pregnancy and further compromises maternal and child health is currently poorly understood. In this review, we evaluate recent scientific literature and describe the suggested links between overweight, gut and low-grade inflammation associated metabolic disorders. We focus on overweight pregnant women and gestational diabetes, and discuss how specific dietary factors, probiotics and long-chain polyunsaturated fatty acids (fish oil), might confer health benefits in combatting against metabolic risk factors.

Comparison of glucose homeostasis parameters between patients with high and low risk of diabetes at 6 weeks and 6 months after sleeve gastrectomy

BACKGROUND

The changes in glucose homeostasis after sleeve gastrectomy (SG) for patients with high (HRD) and low risk (LRD) of developing diabetes have not been investigated.

OBJECTIVE

To compare the glucose homeostasis parameters between patients with HRD and LRD after SG.

SETTING

University hospital in Greece.

METHODS

Thirteen patients were categorized as HRD (9 females, mean body mass index 46.3±1.6 kg/m²) and 10 as LRD (8 females, mean body mass index 45.4±1.7 kg/m²) based on a preoperative 2-hour oral glucose tolerance test (OGTT). OGTT was repeated 6 weeks and 6 months postoperatively. OGTT-derived indices of insulin secretion, insulin sensitivity, and β-cell function (oral disposition index [ODI]) were calculated.

RESULTS

Preoperatively, in the HRD group, fasting and postload glucose levels were higher and the ODIs were lower compared with those in the LRD group. Six weeks postoperatively, glucose levels and ODIs were not different between the 2 groups. However, 6 months postoperatively, the HRD group had demonstrated higher postload glucose levels and lower ODI (0-30) and ODI (0-120) compared with the LRD group. Six weeks postoperatively, insulin levels, early insulin secretion, and insulin resistance indices were decreased compared with preoperative levels only in the HRD group. Six months postoperatively, ODIs and insulin sensitivity indices improved in both groups compared with baseline.

CONCLUSION

Six months after SG, glucose levels and ODIs improved for both HRD and LRD patients; however, postprandial glucose levels and ODI (0-30) and ODI (0-120) in HRD patients did not return to LRD levels. Moreover, during the first 6 postoperative weeks, the changes in glucose homeostasis parameters compared with preoperative levels were different for HRD and LRD patients.

Body fat mass and the proportion of very large adipocytes in pregnant women are associated with gestational insulin resistance

Background/Objectives:

Pregnancy is accompanied by fat gain and insulin resistance. Changes in adipose tissue morphology and function during pregnancy and factors contributing to gestational insulin resistance are incompletely known. We sought to characterize adipose tissue in trimesters 1 and 3 (T1/T3) in normal weight (NW) and obese pregnant women, and identify adipose tissue-related factors associated with gestational insulin resistance.

Subjects/Methods:

Twenty-two NW and 11 obese women were recruited early in pregnancy for the Pregnancy Obesity Nutrition and Child Health study. Examinations and sampling of blood and abdominal adipose tissue were performed longitudinally in T1/T3 to determine fat mass (air-displacement plethysmography); insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR); size, number and lipolytic activity of adipocytes; and adipokine release and density of immune cells and blood vessels in adipose tissue.

Results:

Fat mass and HOMA-IR increased similarly between T1 and T3 in the groups; all remained normoglycemic. Adipocyte size increased in NW women. Adipocyte number was not influenced, but proportions of small and large adipocytes changed oppositely in the groups. Lipolytic activity and circulating adipocyte fatty acid-binding protein increased in both groups. Adiponectin release was reduced in NW women. Fat mass and the proportion of very large adipocytes were most strongly associated with T3 HOMA-IR by multivariable linear regression (R²=0.751, P<0.001).

Conclusions:

During pregnancy, adipose tissue morphology and function change comprehensively. NW women accumulated fat in existing adipocytes, accompanied by reduced adiponectin release. In comparison with the NW group, obese women had signs of adipocyte recruitment and maintained adiponectin levels. Body fat and large adipocytes may contribute significantly to gestational insulin resistance.

Cardiometabolic implications of postpartum weight changes in the first year after delivery

OBJECTIVE

The cumulative effect of postpartum weight retention from each pregnancy in a woman's life may contribute to her ultimate risk of diabetes and vascular disease. However, there is little direct evidence supporting this hypothesis. In this context, we sought to evaluate the cardiometabolic implications of patterns of postpartum weight change and the time course thereof in the first year after pregnancy.

RESEARCH DESIGN AND METHODS

Three hundred five women underwent cardiometabolic characterization at recruitment in pregnancy and at 3 and 12 months postpartum. Based on their respective weight changes between prepregnancy and 3 months postpartum (loss or gain) and between 3 and 12 months postpartum (loss or gain), participants were stratified into four groups: loss/loss, gain/loss, loss/gain, and gain/gain.

RESULTS

Most women (81.0%) had higher weight at 3 months postpartum compared with prepregnancy. Between 3 and 12 months, most women (74.4%) lost weight. At 3 months, there were modest differences between the four groups in mean adjusted LDL cholesterol (P = 0.01) and apolipoprotein-B (apoB; P = 0.02) but no significant differences in adjusted blood pressure, fasting and 2-h glucose, HDL, triglycerides, homeostasis model assessment of insulin resistance (HOMA-IR), adiponectin, and C-reactive protein. By 12 months postpartum, however, clear gradients emerged, with mean adjusted diastolic blood pressure (P = 0.02), HOMA-IR (P = 0.0003), LDL (P = 0.001), and apoB (P < 0.0001) all progressively increasing from the loss/loss group to gain/loss to loss/gain to gain/gain. Similarly, at 12 months, mean adjusted adiponectin showed a stepwise decrease from loss/loss to gain/loss to loss/gain to gain/gain (P = 0.003).

CONCLUSIONS

An adverse cardiometabolic profile emerges as early as 1 year postpartum in women who do not lose weight between 3 and 12 months after delivery.

The role of exercise in reducing the risks of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is the most common medical complication of pregnancy and is particularly prevalent among obese women. Both GDM and obesity confer significant comorbidities for the mother and her offspring, including perinatal complications, excessive fetal growth and long-term risks for maternal and offspring obesity and diabetes. Exercise has well-documented health benefits and reduces peripheral insulin resistance in nonpregnant individuals, a major risk factor for the development of diabetes. Observational studies conducted in large population-based cohorts suggest that women who are the most active before pregnancy are less insulin-resistant in late pregnancy and have lower rates of GDM. This article will review the evidence supporting a role for exercise in the prevention of GDM, the management of glycemic control in women with established GDM, and the reduction of GDM-associated maternal and offspring health consequences. Wherever possible, the discussion will focus on studies carried out on obese women. However, there are many areas where strong evidence is lacking in obese populations, and it may be inferred from similar studies performed in normal weight pregnant women.

Physical activity before and during pregnancy and risk of abnormal glucose tolerance among Hispanic women

AIM

Women diagnosed with abnormal glucose tolerance and gestational diabetes mellitus are at increased risk for subsequent type 2 diabetes, with higher risks in Hispanic women. Studies suggest that physical activity may be associated with a reduced risk of these disorders; however, studies in Hispanic women are sparse.

METHODS

We prospectively evaluated this association among 1241 Hispanic participants in Proyecto Buena Salud. The Pregnancy Physical Activity Questionnaire was used to assess pre, early, and mid pregnancy physical activity. Medical records were abstracted for pregnancy outcomes.

RESULTS

A total of 175 women (14.1%) were diagnosed with abnormal glucose tolerance and 57 women (4.6%) were diagnosed with gestational diabetes. Increasing age and body mass index were strongly and positively associated with risk of gestational diabetes. We did not observe statistically significant associations between total physical activity or meeting exercise guidelines and risk. However, after adjusting for age, BMI, gestational weight gain, and other important risk factors, women in the top quartile of moderate-intensity activity in early pregnancy had a decreased risk of abnormal glucose tolerance (odds ratio=0.48, 95% Confidence Interval 0.27-0.88, Ptrend=0.03) as compared to those in the lowest quartile. Similarly, women with the highest levels of occupational activity in early pregnancy had a decreased risk of abnormal glucose tolerance (odds ratio=0.48, 95% Confidence Interval 0.28-0.85, Ptrend=0.02) as compared to women who were unemployed.

CONCLUSION

In this Hispanic population, total physical activity and meeting exercise guidelines were not associated with risk. However, high levels of moderate-intensity and occupational activity were associated with risk reduction.

Predictors and clinical implications of a false negative glucose challenge test in pregnancy

OBJECTIVE

A common approach to screening for glucose intolerance in pregnant women is the use of a 50g glucose challenge test (GCT) in the late second trimester, followed by a diagnostic oral glucose tolerance test (OGTT) when the GCT is positive (1-hour post-challenge blood glucose ≥ 7.8 mmol/L). As women with a negative GCT do not undergo the diagnostic OGTT, it is possible that they could have undiagnosed gestational diabetes (GDM) or gestational impaired glucose tolerance (GIGT). Thus, we sought to characterize predictors of a false negative GCT and its clinical implications.

METHODS

Two hundred two women with a negative GCT screening test underwent subsequent OGTT, which enabled their stratification into two groups: (1) those with normal glucose tolerance on OGTT (n = 166) and (2) those with either GDM (n = 8) or GIGT (n = 28).

RESULTS

The 36 women found to have GDM or GIGT at the time of OGTT had higher GCT glucose values than those with normal glucose tolerance (mean 6.6 mmol/L vs. 5.9 mmol/L, P < 0.001), as well as poorer insulin sensitivity (P = 0.004) and pancreatic beta-cell function (P < 0.001). On logistic regression analysis, the only significant independent predictor of GDM/GIGT was the GCT glucose value (OR 2.19; 95% CI 1.40 to 3.41, P < 0.001). However, there was no clear GCT glucose threshold for identifying GDM/GIGT, consistent with its modest area under the receiver operating characteristic curve (0.71). Importantly, there were also no differences between the two groups in median length of gestation, median birth weight, prevalence of macrosomia, or proportion of low Apgar scores.

CONCLUSION

False negative GCTs cannot be readily predicted by risk factors. However, their clinical implications at delivery may be benign.

Insulin resistance as estimated by the homeostatic method at diagnosis of gestational diabetes: estimation of disease severity and therapeutic needs in a population-based study

BACKGROUND

Chronic insulin resistance, exacerbated in the course of pregnancy, is an important pathophysiologic mechanism of gestational diabetes mellitus (GDM). We hypothesise that the degree of insulin resistance, assessed at diagnosis of GDM, is a parameter of its pathophysiologic heterogeneity and/or severity. Thus, it offers potential to open new avenues for the personalization of therapy in affected women.

METHODS

1254 Polish Caucasian women with GDM were recruited into the study. The following parameters were assessed in the course of the study: body mass index (BMI), parity, weight gain during pregnancy, glycated haemoglobin, glucose level during an oral glucose tolerance test (OGTT), insulin, insulin resistance and insulin secretion. The severity of GDM was assessed based on insulin use and daily insulin dose during gestation. In order to evaluate insulin secretion and insulin resistance the homeostatic method was used (HOMA-B and HOMA-IR, respectively). We compared all the metabolic parameters and methods of treatment of GDM in women subdivided by quartiles of insulin resistance.

RESULTS

The HOMA-IR in the whole population ranged from 0.34 to 20.39. The BMI, fasting insulin, fasting glucose and insulin dose per day increased along with increasing quartiles (HOMA-IR > 1.29). We observed a decrease of HOMA-B in the third quartile (1.92-2.89) compared with the first quartile (0.34-1.29). Insulin treatment was associated with HOMA-IR (<1.29 vs. >2.89), OR: 3.37, fasting glucose (≤6.11 vs. >6.11 mmol/dl), OR: 2.61, age (≤30 vs. >30 y. o.), OR: 1.54, and BMI (<25 vs. ≥25 kg/m2), OR: 1.45. Maximum insulin dose was associated with HOMA-IR, OR: 2.00, after adjustment for family history of diabetes, and 2-h OGTT glucose.

CONCLUSION

Insulin resistance assessed by the HOMA index at diagnosis is associated with the severity and pathophysiological heterogeneity of GDM. A HOMA-IR >1.29 points to the major role of insulin resistance, indicating the need for a treatment aimed at improving tissue sensitivity to insulin. A HOMA-IR 1.29-2.89 suggests reduced insulin secretion, which is an indication for the introduction of insulin therapy. A HOMA-IR >2.89 indicates insufficient compensation for insulin resistance, which suggests the need for a treatment aimed at improving susceptibility of tissues to insulin combined with insulin therapy.

Maternal/fetal determinants of insulin resistance in women during pregnancy and in offspring over life

Insulin resistance is a component of the pathophysiology of both type 2 diabetes and gestational diabetes mellitus (GDM), but is also characteristic of normal glycemic physiology during pregnancy. In recent years, many studies have tried to understand determinants of insulin resistance in normal pregnancy and GDM, revealing that the placenta is capable of secreting many cytokines and hormones, classically considered as adipokines. More specifically, it appears that leptin and TNFα could be implicated in gestational insulin resistance and GDM pathophysiology. In addition, the maternal metabolic milieu was also identified as a key determinant of later insulin resistance in offspring, a phenomenon often described as 'fetal programming'. This article reviews the established risk factors and the more novel suspected biomarkers involved in maternal insulin resistance during pregnancy as well as the maternal and early life determinants of insulin resistance in offspring later in their life. We are also highlighting recent reports of the potential mechanisms involved in 'programming' of insulin resistance such as epigenetic modulation.

Association between adiponectin and tumor necrosis factor-alpha levels at eight to fourteen weeks gestation and maternal glucose tolerance: the Parity, Inflammation, and Diabetes Study

OBJECTIVE

Inflammation may influence gestational hyperglycemia, but to date, the data from observational studies is largely limited to results from the third trimester of pregnancy. Our objective was to evaluate first trimester adipocytokine levels. We sought to determine whether first trimester adiponectin and tumor necrosis factor-alpha (TNF)-alpha concentrations were independently associated and predictive of maternal glucose tolerance, as measured by the 1-hour glucose challenge test (GCT), after adjustment for maternal lifestyle behaviors and body mass index (BMI).

MATERIAL AND METHODS

Prospective study of pregnant women (n=211) enrolled in the Parity, Inflammation, and Diabetes Study. Nonfasting serum levels of adiponectin and TNF-r2 were measured at 8-14 weeks of pregnancy. GCT results were abstracted from electronic prenatal records. Multiple linear regression models were developed to determine the association of adiponectin and TNF-r2 levels with response to the GCT, adjusting for demographics, pregravid dietary intake and physical activity, first trimester BMI, and gestational weight gain.

RESULTS

At baseline, higher adiponectin concentrations were inversely and statistically significantly associated with maternal response to the GCT [regression coefficient (β) -0.68; 95% confidence interval (CI): -1.29, -0.06). Adjustment for lifestyle factors did not alter the association of adiponectin with the GCT (β -0.74; 95% CI: -1.43, -0.05). After adjustment for first trimester BMI, the association of adiponectin was attenuated and no longer significant (β -0.46; 95% CI: -1.15, 0.24). TNF-r2 levels were not associated with the GCT (β -0.003; 95% CI: -0.011, 0.005).

CONCLUSIONS

First trimester adiponectin levels are not predictive of the 1-hour GCT response, but may be a marker for the effect of maternal BMI on glucose response to the GCT.

Circadian variation in the response to the glucose challenge test in pregnancy: implications for screening for gestational diabetes mellitus

OBJECTIVE

A common approach to screening for gestational diabetes mellitus (GDM) is the universal testing of all pregnant women with a 1-h, 50-g glucose challenge test (GCT), followed by a diagnostic oral glucose tolerance test (OGTT) in those in whom the GCT is positive (≥7.8 mmol/L). More important, the GCT is performed at any time of day, but there has been limited study of the effect of time of day on test performance. Thus, using their subsequent OGTT (performed in the morning), we sought to characterize the metabolic function of women with positive GCTs in relation to the timing of their test.

RESEARCH DESIGN AND METHODS

A total of 927 women with positive GCTs underwent a 3-h 100-g OGTT. They were stratified into four groups by time of day (hours) of their GCT: <0900 (n = 171), 0900-1059 (n = 288), 1100-1259 (n = 189), and ≥1300 (n = 279).

RESULTS

On the OGTT, the prevalence of GDM progressively decreased across the GCT groups from <0900 h (26.9%) to 0900-1059 h (25.0%) to 1100-1259 h (21.7%) to ≥1300 h (21.5%; P = 0.0022). After adjustment for GDM risk factors, mean adjusted glucose area under the curve (AUC(gluc)) similarly decreased across the groups, while insulin sensitivity (Matsuda index) and β-cell function (Insulin Secretion-Sensitivity Index-2) progressively increased (all P < 0.0001). In particular, compared with the <0900- and 0900-1059-h groups, women whose positive GCT occurred after 1300 h had superior metabolic function, as evidenced by lower AUC(gluc), higher insulin sensitivity, and better β-cell function (all P ≤ 0.0097).

CONCLUSIONS

Among women with a positive GCT, those tested in the afternoon have better metabolic function and a lower risk of GDM on subsequent OGTT.

The potential impact of physical activity during pregnancy on maternal and neonatal outcomes

INTRODUCTION

Pregnancy is a critical period of body weight regulation. Maternal obesity and excessive gestational weight gain have become increasingly common and contribute to poor obstetrical outcomes for mother and baby. Regular participation in physical activity may improve risk profiles in pregnant women.

PURPOSE AND METHODS

Our objectives were to provide an overview of maternal-fetal exercise physiology, summarize current evidence on the effects of physical activity during pregnancy on maternal-fetal outcomes, and review the most recent clinical practice guidelines. In addition, we summarize the findings in the context of the current obesity epidemic and discuss implications for clinical practice. A literature review was completed in which we queried OVID (Medline), EMBASE, and PSYCHINFO databases with title words "exercise or physical activity" and "pregnancy or gestation" from 1950 to March 1, 2010. A total of 212 articles were selected for review.

RECOMMENDATIONS

Care providers should recommend physical activity to most pregnant women (i.e., those without contraindications) and view participation as a safe and beneficial component of a healthy pregnancy.

TARGET AUDIENCE

Obstetricians & Gynecologists and Family Physicians.

LEARNING OBJECTIVES

After participating in this CME activity, physicians should be better able to classify the potential impact of physical activity on maternal glycemic control and fetal growth outcomes. Assess maternal lifestyle and provide recommendations on appropriate gestational weight gain, evaluate pregnant women for contraindications to physical activity participation, make individualized recommendations for exercise participation, and educate patients on the merits of physical activity for health benefit.

Prenatal exercise research

In this review of recent research on prenatal exercise, studies from several different countries suggest that only approximately 40% of pregnant women exercise, even though about 92% are encouraged by their physicians to exercise, albeit with some 69% of the women being advised to limit their exercise. A moderate exercise regime reputedly increases infant birthweight to within the normal range, but only if exercise is decreased in late pregnancy. Lower intensity exercise such as water aerobics has decreased low back pain more than land-based physical exercise. Heart rate and blood pressure have been lower following yoga than walking, and complications like pregnancy-induced hypertension with associated intrauterine growth retardation and prematurity have been less frequent following yoga. No studies could be found on tai chi with pregnant women even though balance and the risk of falling are great concerns during pregnancy, and tai chi is one of the most effective forms of exercise for balance. Potential underlying mechanisms for exercise effects are that stimulating pressure receptors during exercise increases vagal activity which, in turn, decreases cortisol, increases serotonin and decreases substance P, leading to decreased pain. Decreased cortisol is particularly important inasmuch as cortisol negatively affects immune function and is a significant predictor of prematurity. Larger, more controlled trials are needed before recommendations can be made about the type and amount of pregnancy exercise.

Preeclampsia and gestational diabetes mellitus: pre-conception origins?

Preeclampsia (PE) and gestational diabetes mellitus (GDM) are two of the most common medical complications of pregnancy, with risks for both mother and child. Like many other antepartum complications, PE and GDM occur only in pregnancy. However, it is not clear if pregnancy itself is the cause of these complications or it these conditions are caused by factors that existed prior to gestation. In this paper, we hypothesize that although the clinical findings of PE and GDM are first noted during pregnancy, the origins of both conditions may actually precede pregnancy. We further hypothesize that pathophysiologic changes underlying PE and GDM are present prior to pregnancy, but remain undetected in the non-gravid state either because pregnancy is the trigger that makes these pathologies become clinically detectable or because there has been limited prospective longitudinal data comparing the pre-gravid and antepartum status of women that go on to develop these conditions. Rigorous prospective cohort studies in which women undergo serial systematic evaluation in the pre-conception period, throughout pregnancy and into the postpartum are ideally needed to test this hypothesis of pre-conception origins of PE and GDM. In this context, we are creating a pre-conception cohort, involving about 5000 couples who plan to have a baby within six months in Liuyang county in the Chinese province of Hunan. Results from this pre-conception cohort program should be able to provide definitive answer to the question of whether the underpinnings of PE and GDM originate prior to pregnancy. Ultimately, the significance of addressing this hypothesis is underscored by its potential implications for targeted interventions that could be designed to (i) prevent the deleterious effects of PE/GDM and (ii) thereby interrupt the vicious cycle of disease that links affected women and their offspring.

Physical activity during pregnancy and risk of hyperglycemia

OBJECTIVE

To determine the association between moderate and vigorous physical activities (MVPA) during midpregnancy and the risk of hyperglycemia.

METHODS

Data were from 1437 pregnant women. Frequency, duration, and intensity of MVPA during the previous 7 days were collected via questionnaire at 17-22 weeks' gestation. Modes of MVPA included work, recreation, transportation, caregiving, and indoor and outdoor household activities. Hyperglycemia was defined as a glucose concentration ≥130 mg/dL on a 1-hour, 50-g glucose challenge test or gestational diabetes mellitus (GDM) assessed at ~27 weeks' gestation. Multivariable Poisson regression estimated risks of hyperglycemia associated with total and mode-specific MVPA.

RESULTS

There were 269 women (18.7%) with hyperglycemia. Any metabolic equivalent (MET) hours/week of recreational MVPA was associated with a 27% lower risk of hyperglycemia (adjusted relative risk, [aRR] 0.73, 95% confidence interval [95%CI] 0.54-0.99). Multiplicative interaction terms were significant for prepregnancy body mass index (BMI) and recreational MVPA (p=0.01). Among women with prepregnancy BMI <25 kg/m(2), recreational MVPA was associated with a 48% lower risk of hyperglycemia (aRR 0.52, 95%CI 0.33-0.83) compared to women who reported none. There was no association of hyperglycemia and recreational MVPA among women with prepregnancy BMI <25 kg/m(2).

CONCLUSIONS

Recreational MVPA during pregnancy is associated with a lower risk of hyperglycemia, specifically among women with prepregnancy BMI <25 kg/m(2). Further research is warranted to determine recommended amounts and intensities of physical activity and to discern whether there are differences in the effects of physical activity between specific modes of physical activity or among subgroups of women in relation to hyperglycemia.

Impact of maternal physical activity and infant feeding practices on infant weight gain and adiposity

Increasing evidence supports the contribution of intrauterine environmental exposures on obesity risk in offspring. Few studies have included maternal and infant lifestyle factors. Our objective was to study the impact of maternal physical activity, infant feeding, and screen time on offspring weight gain and adiposity. In a prospective cohort study, 246 mothers underwent testing during pregnancy to assess glucose tolerance status and insulin sensitivity. Anthropometry and questionnaires on physical activity, infant feeding, and screen time were completed. Multiple-linear regression was performed to examine the impact of maternal and infant factors on infant weight gain and weight-for-length z-score at 1 year. Infant weight outcomes were negatively predicted by maternal pregravid vigorous/sport index and exclusive breastfeeding duration. After adjustment, each unit increase in maternal pregravid vigorous/sport index decreased infant weight gain by 218.6 g (t = 2.44, P = 0.016) and weight-for-length z-score by 0.20 (t = 2.17, P = 0.031). Each month of exclusive breastfeeding reduced infant weight gain by 116.4 g (t = 3.97, P < 0.001) and weight-for-length z-score by 0.08 (t = 2.59, P = 0.01). Maternal pregravid physical activity and exclusive breastfeeding duration are associated with weight gain and adiposity as early as 1 year of age.

Effect of dietary and lifestyle factors on the risk of gestational diabetes: review of epidemiologic evidence

Gestational diabetes mellitus (GDM), defined as glucose intolerance with onset or first recognition in pregnancy, is a common pregnancy complication and a growing health concern. GDM has been related to significant short-term and long-term adverse health outcomes for both mothers and offspring. Importantly, this number is increasing with the increasing burden of obesity among women of reproductive age. Collectively, these data highlight the significance of understanding risk factors, in particular modifiable factors, for GDM and of preventing GDM among high-risk populations. Research in the past decade has identified a few diet and lifestyle factors that are associated with GDM risk. This review provides an overview of emerging diet and lifestyle factors that may contribute to the prevention of GDM. It also discusses major methodologic concerns about the available epidemiologic studies of GDM risk factors.

Pregravid physical activity, dietary intake, and glucose intolerance during pregnancy

OBJECTIVES

To ascertain prepregnancy physical activity and dietary intake from a sample of women in early pregnancy and estimate the effect of prepregnancy lifestyle behaviors on the 1-hour glucose challenge test (GCT).

METHODS

We conducted a prospective analysis of a racially diverse urban-based sample of 152 pregnant women in the first trimester who were participants in the Parity, Inflammation and Diabetes (PID) study. Dietary intake before pregnancy was assessed using a modified version of the Block Rapid Food Screener, and leisure time physical activity before pregnancy was assessed using the Baecke questionnaire. Test results from a nonfasting oral GCT conducted between 26 and 28 weeks were abstracted from the medical record. Participants were classified as having a positive GCT if the blood glucose measurement was ≥140 mg/dL and as negative with a blood glucose measurement <140 mg/dL. We constructed a series of multiple logistic regression models, adjusting for potential confounders to determine if prepregnancy dietary intake and leisure activity were associated with response to the GCT.

RESULTS

Women with higher prepregnancy leisure activity scores were 68% less likely to have a 1-hour GCT response ≥140mg/dL. However, there was no association between dietary intake and response to the GCT.

CONCLUSIONS

Our data suggest that prevention of an abnormal GCT result should include practices to encourage women of reproductive age to engage in leisure physical activity in advance of planning a pregnancy.

Definition, epidemiology, risk factors

Gestational diabetes mellitus is defined as glucose intolerance that begins or is first recognized during pregnancy. Its prevalence, generally situated between 2-6%, may reach 10-20% in high-risk populations, with an increasing trend across most racial/ethnic groups studied. Among traditional risk factors, previous gestational diabetes, advanced maternal age and obesity have the highest impact on gestational diabetes risk. Racial/ethnic origin and family history of type 2 diabetes have a significant but moderate impact (except for type 2 diabetes in siblings). Several non traditional factors have been recently characterized, either physiological (low birthweight and short maternal height) or pathological (polycystic ovaries). The multiplicity of risk factors and their interactions results in a low reliability of risk prediction on an individual basis.

Obesity and diabetes in mothers and their children: can we stop the intergenerational cycle?

Obesity prevalence in the United States has reached an alarming level. Consequently, more young women are entering pregnancy with body mass indices of at least 30 kg/m(2). While higher maternal weight entering pregnancy is related to several adverse pregnancy outcomes, some of the strongest and most compelling data to date have linked prepregnancy obesity to gestational diabetes mellitus (GDM). The mechanisms by which excess maternal weight influences metabolic dysfunction in pregnancy are similar to those in obese nonpregnant women; adipocytes are metabolically active and release a number of hormones implicated in insulin resistance. Heavier mothers are also more likely to have higher glucose levels that do not exceed the cutoff for GDM, but nevertheless predict poor perinatal outcomes. Longer-term complications of GDM include increased risk of maternal type 2 diabetes and offspring obesity. Promising intervention studies to decrease the intergenerational cycle of obesity and diabetes are currently underway.

Does exercise have a role in the management of gestational diabetes mellitus?

Gestational diabetes mellitus (GDM) is associated with a marked increase in the long-term risk of type 2 diabetes and adverse pregnancy outcomes. Engaging in vigorous recreational physical activity prior to and during pregnancy significantly reduces the risk of developing GDM. In contrast, evidence of a therapeutic effect from participation in a structured exercise training regimen, although promising, is limited and requires further more substantial investigation. This paper briefly reviews the pathophysiology of GDM, the evidence related to physical activity participation and exercise regimen intervention on GDM, and the clinical considerations required for prescribing exercise.

Impact of maternal metabolic abnormalities in pregnancy on human milk and subsequent infant metabolic development: methodology and design

BACKGROUND

Childhood obesity is on the rise and is a major risk factor for type 2 diabetes later in life. Recent evidence indicates that abnormalities that increase risk for diabetes may be initiated early in infancy. Since the offspring of women with diabetes have an increased long-term risk for obesity and type 2 diabetes, the impact of maternal metabolic abnormalities on early nutrition and infant metabolic trajectories is of considerable interest. Human breast milk, the preferred food during infancy, contains not only nutrients but also an array of bioactive substances including metabolic hormones. Nonetheless, only a few studies have reported concentrations of metabolic hormones in human milk specifically from women with metabolic abnormalities. We aim to investigate the impact of maternal metabolic abnormalities in pregnancy on human milk hormones and subsequently on infant development over the first year of life. The objective of this report is to present the methodology and design of this study.

METHODS/DESIGN

The current investigation is a prospective study conducted within ongoing cohort studies of women and their offspring. Pregnant women attending outpatient obstetrics clinics in Toronto, Canada were recruited. Between April 2009 and July 2010, a total of 216 pregnant women underwent a baseline oral glucose tolerance test and provided medical and lifestyle history. Follow-up visits and telephone interviews are conducted and expected to be completed in October 2011. Upon delivery, infant birth anthropometry measurements and human breast milk samples are collected. At 3 and 12 months postpartum, mothers and infants are invited for follow-up assessments. Interim telephone interviews are conducted during the first year of offspring life to characterize infant feeding and supplementation behaviors.

DISCUSSION

An improved understanding of the link between maternal metabolic abnormalities in pregnancy and early infant nutrition may assist in the development of optimal prevention and intervention strategies and in the protection of nutritionally vulnerable offspring who are at risk for obesity and diabetes later in life.

Gestational diabetes: risk factors and recent advances in its genetics and treatment

The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study of over 23000 diabetes-free pregnancies has shown that at a population level an unequivocal linear relationship exists between maternal glucose concentrations around the beginning of the third trimester of pregnancy and the risk of their baby being born above the ninetieth centile for weight. With the rising incidence of gestational diabetes (GDM) across the developed world, largely paralleling the increased prevalence of obesity, there has been a sharp increase in the risk of pregnancy complications developing related to the birth of macrosomic babies. The associated additional long-term complications of GDM pregnancies means that in the future there is likely to be a large increase in the incidence of type 2 diabetes and associated conditions in both the mothers and their affected offspring. The present review seeks to highlight recent advances and remaining gaps in knowledge about GDM in terms of its genetics (where some of the recently discovered polymorphic risk factors for type 2 diabetes have also proved to be risk factors for GDM) and its treatment by diet, exercise and drugs.

Gestational diabetes and postpartum physical activity: evidence of lifestyle change 1 year after delivery

Although women with gestational diabetes mellitus (GDM) are advised to incorporate physical activity into their lifestyle in order to reduce their risk of developing type 2 diabetes (T2DM), it is recognized that new mothers face barriers to postpartum exercise. Thus, we sought to determine whether, following the diagnosis of GDM, women indeed alter their postpartum physical activity patterns, as compared to their peers without GDM. In this prospective observational cohort study, we assessed the physical activity patterns of 238 white women (58 with GDM, 180 without GDM) in the year before pregnancy and in the year following delivery, using the Baecke questionnaire, which evaluates the following three domains of physical activity: work, sport activity, and nonsport leisure-time activity. Before diagnosis with GDM, women reported lower pregravid sport (P = 0.010) and leisure-time activity (P = 0.013), compared to their peers without GDM. By 1 year postpartum, however, there were no longer significant differences between the GDM and non-GDM groups in either sport or leisure-time activity (P = 0.078 and P = 0.957, respectively). In particular, women with GDM significantly increased their leisure-time activity over the first year postpartum (F = 10.1, P = 0.002), whereas the non-GDM group did not (F = 0.00, P = 0.984). Indeed, on multiple linear regression analysis, GDM independently predicted an increase in leisure-time activity between 1 year pregravid and 1 year postpartum (t = 2.55, P = 0.012). Furthermore, this significant relationship persisted even after adjustment for the finding of prediabetes/diabetes at 3 months postpartum (t = 2.83, P = 0.005). In conclusion, women with GDM successfully increased their leisure-time activity in the first year postpartum, reflecting an element of lifestyle change following this diagnosis.