Regular exercise during pregnancy to prevent gestational diabetes: a randomized controlled trial

Gestational diabetes mellitus: does an effective prevention strategy exist?

The overall incidence of gestational diabetes mellitus (GDM) is increasing worldwide. Preventing pathological hyperglycaemia during pregnancy could have several benefits: a reduction in the immediate adverse outcomes during pregnancy, a reduced risk of long-term sequelae and a decrease in the economic burden to healthcare systems. In this Review we examine the evidence supporting lifestyle modification strategies in women with and without risk factors for GDM, and the efficacy of dietary supplementation and pharmacological approaches to prevent this disease. A high degree of heterogeneity exists between trials so a generalised recommendation is problematic. In population studies of dietary or combined lifestyle measures, risk of developing GDM is not improved and those involving a physical activity intervention have yielded conflicting results. In pregnant women with obesity, dietary modification might reduce fetal macrosomia but in these patients, low compliance and no significant reduction in the incidence of GDM has been observed in trials investigating physical activity. Supplementation with probiotics or myoinositol have reduced the incidence of GDM but confirmatory studies are still needed. In randomized controlled trials, metformin does not prevent GDM in certain at-risk groups. Given the considerable potential for reducing disease burden, further research is needed to identify strategies that can be easily and effectively implemented on a population level.

Interventions to improve physical activity during pregnancy: a systematic review on issues of internal and external validity using the RE-AIM framework

BACKGROUND

Physical activity (PA) during pregnancy has significant health benefits for the mother and her child; however, many women reduce their activity levels during pregnancy and most are not sufficiently active. Given the important health benefits of PA during pregnancy, evidence that supports research translation is vital.

OBJECTIVES

To determine the extent to which physical activity interventions for pregnant women report on internal and external validity factors using the RE-AIM framework (reach, efficacy/effectiveness, adoption, implementation, and maintenance).

SEARCH STRATEGY

Ten databases were searched up to 1 June 2015. Eligible published papers and unpublished/grey literature were identified using relevant search terms.

SELECTION CRITERIA

Studies had to report on physical activity interventions during pregnancy, including measures of physical activity during pregnancy at baseline and at least one point post-intervention. Randomised controlled trials and quasi-experimental studies that had a comparator group were included.

DATA COLLECTION AND ANALYSIS

Reporting of RE-AIM dimensions were summarised and synthesised across studies.

MAIN RESULTS

The reach (72.1%) and efficacy/effectiveness (71.8%) dimensions were commonly reported; however, the implementation (28.9%) and adoption (23.2%) dimensions were less commonly reported and no studies reported on maintenance.

CONCLUSIONS

This review highlights the under-reporting of issues of contextual factors in studies of physical activity during pregnancy. The translation of physical activity interventions during pregnancy could be improved through reporting of representativeness of participants, clearer reporting of outcomes, more detail on the setting and staff who deliver interventions, costing of interventions and the inclusion of process evaluations and qualitative data.

TWEETABLE ABSTRACT

The systematic review highlights the under-reporting of contextual factors in studies of physical activity during pregnancy.

The Association Between Physical Activity During Pregnancy and Gestational Diabetes Mellitus: A Case-Control Study

BACKGROUND

Gestational diabetes mellitus is one of the most common complications of pregnancy. Physical activity is associated with a lower risk of type 2 diabetes mellitus. A recent meta-analysis study suggested that more research is needed to investigate the type, duration and intensity of physical activity that can help to reduce the risk of gestational diabetes mellitus.

OBJECTIVES

The present study aimed to understand the association between physical activity and gestational diabetes mellitus through comparing the type and intensity of physical activity performed by pregnant females with gestational diabetes and healthy pregnant females in the first 20 weeks of their pregnancy.

PATIENTS AND METHODS

In the current case-control study, 100 pregnant females with gestational diabetes mellitus as the case group and 100 pregnant females as the non-diabetic control group were recruited. The age range of the participants was 18 - 40 years with the gestation of 20 - 28 weeks. To diagnose gestational diabetes mellitus using the criteria introduced by carpenter and coustan females with abnormal glucose challenge test (> 140 mg/dL) were asked to perform the three-hour 100 g oral glucose tolerance test. The details of physical activity were collected by a modified version of the pregnancy physical activity questionnaire. Anthropometric and relevant data were recorded for all of the participants. Data were analyzed by SPSS version 21. Risk estimates were obtained by logistic regression and adjusted for confounders.

RESULTS

Females who had low total physical activity according to the pregnancy physical activity questionnaire during early pregnancy were at a significantly higher risk of developing gestational diabetes mellitus (OR = 4.12, 95% CI (2.28 - 7.43), P = 0.001) compared to the ones who reported higher levels of physical activity. Moreover, after adjusting for age, body mass index (BMI), gravidity and a family history of diabetes, females with low physical activity in the domain of transportation activity during 20 weeks of pregnancy were at a significantly higher risk of developing gestational diabetes mellitus. The statistical findings indicate that females with the low intensity of sedentary, light and moderate physical activity are at a higher risk of developing gestational diabetes mellitus (OR 2.32; 95% CI 1.21-4.43, P = 0.010, OR 6.26; 95% CI 2.95 - 13.30, P = 0.001 and OR 6.73; 95% CI 3.15 - 14.38, P = 0.001) compared to females with a higher intensity of sedentary, light and moderate physical activity.

CONCLUSIONS

The amount and intensity of physical activity during pregnancy is associated with a lower risk of gestational diabetes mellitus. As a result, the pregnant Iranian females have to be encouraged to do regular daily physical activity during pregnancy, if there is no specific contraindication to it.

Physical activity of relatively high intensity in mid-pregnancy predicts lower glucose tolerance levels

INTRODUCTION

Physical activity (PA) is recommended as part of therapy for patients with impaired glucose tolerance. Whether such recommendations are also justified for pregnant women is less well established. We investigated the association between PA and glucose tolerance in pregnancy.

MATERIAL AND METHODS

A non-selective sample of 217 pregnant women was recruited at a routine 20 week ultrasound examination. Participants answered the International Physical Activity Questionnaire (IPAQ) about frequency, intensity and duration of daily physical activity in the past 7 days and underwent oral glucose tolerance testing (OGTT) between 24 and 28 weeks. A subset of 72 overweight/obese pregnant women wore a pedometer for 1 week with assessment of IPAQ score and pedometric correlations to this.

RESULTS

Of the sample, 177 attended for OGTT; 51% were overweight or obese. The mean (SD) fasting glucose was 4.5 (0.4) mmol/L, and 12% had gestational diabetes mellitus. Only one-third engaged in vigorous PA. After adjustment for pre-pregnancy BMI, age and parity, those engaging in vigorous PA had significantly lower fasting glucose levels (by 0.15 mmol/L, 95% CI 0.03-0.27) compared with those not vigorously active. This decrease was similar in both normal and overweight/obese women. There were fewer cases of gestational diabetes (p = 0.03) among the vigorously active women (3/56; 5%) than among those who were not active (19/121; 16%). No association with glucose tolerance was observed for physical activity of moderate intensity.

CONCLUSIONS

Only vigorous physical activity appears beneficial with respect to maternal glucose tolerance, both among normal, overweight and obese women.

Physical activity, sedentary behaviors and risk of gestational diabetes mellitus: a population-based cross-sectional study in Tianjin, China

OBJECTIVE

Physical activity in a nonpregnant state or before pregnancy reduces the risk of type 2 diabetes and is also associated with reduced risk of gestational diabetes mellitus (GDM). However, it is uncertain whether physical activity during pregnancy reduces the risk of GDM.

DESIGN AND METHODS

Using an established universal screening system in Tianjin, China, we prospectively recruited 11 450 pregnant women within the 12th gestational week from 2010 to 2012. These women underwent a 50-g 1-h glucose challenge test (GCT) at 24-28 weeks of gestation and a 75-g 2-h oral glucose tolerance test if GCT glucose ≥7.8mmol/L. GDM was defined according to the International Association of Diabetes and Pregnancy Study Group's criteria. Self-reported physical activity in the last month was collected at GCT time using a validated questionnaire.

RESULTS

GDM developed in 7.3% (n=840) of the women. Women with GDM were less likely to be engaged in moderate-to-high physical activity during pregnancy than those without (79.8% vs 81.6%, P=0.191). Moderate-to-high physical activity during pregnancy was associated with decreased risk of GDM (multivariable odds ratio (OR): 0.81, 95% confidence interval (CI): 0.67-0.97). Sitting at home for 2-4h per day and >4h per day were associated with significantly increased risk of GDM (multivariable OR of sitting time for 2-4h vs <2h: 1.59, 95% CI: 1.18-2.15; OR of sitting time for >4h vs <2h: 1.73, 95% CI: 1.22-2.43).

CONCLUSIONS

Increased physical activity during pregnancy was associated with reduced GDM risk, whereas sedentary lifestyle was associated with increased GDM risk among Chinese pregnant women.

Prediction and prevention of Gestational Diabetes: an update of recent literature

A diagnosis of Gestational Diabetes (GDM) confers adverse risk to the health of the mother and fetus both in pregnancy and later life. The background rate in pregnancy varies between 2 and 14% with incidences reported to be as high as 40% in obese populations. GDM diagnoses are escalating because of rising numbers of overweight and obesity in the reproductive age group but also because of different screening and diagnostic criteria. Lifestyle modification in those diagnosed with GDM has been proven to be an effective treatment in attenuating the metabolic dysregulation associated with this and potentially avoiding the need for medical therapy with either metformin or insulin. Emerging evidence in previous years suggests lifestyle interventions (dietary±physical activity and behavior modification) either pre-pregnancy or antenatally may reduce the incidence of GDM. The first trimester is also becoming an important interrogation period for the prediction of many adverse obstetric outcomes including abnormal glucose metabolism. This review outlines the most contemporary evidence on the prediction and non-pharmacological antenatal prevention strategies used for Gestational Diabetes.

Benefits of aerobic or resistance training during pregnancy on maternal health and perinatal outcomes: A systematic review

OBJECTIVE

To understand what evidence exists with regard to maternal and offspring benefits of aerobic and/or resistance training during pregnancy.

METHODS

Systematic review of RCTs (published until May 2015) with healthy pregnant women and focusing on the benefits of exercise interventions on maternal health or perinatal outcomes. Studies were ranked as high/low quality, and a level of evidence was established according to the number of high-quality studies and consistency of the results.

RESULTS

61 RCTs were analyzed. The evidence for a benefit of combined exercise [aerobic+resistance (muscle strength)] interventions on maternal cardiorespiratory fitness and prevention of urinary incontinence was strong. A weak or insufficient level of evidence was found for the rest of interventions and outcomes

CONCLUSION

The exercise modality that seems to induce a more favorable effect on maternal health is the combination of aerobic and resistance exercises during pregnancy.

Hemoglobin A1c as screening for gestational diabetes mellitus in Nordic Caucasian women

BACKGROUND

Gestational diabetes mellitus (GDM) increases the risk for preeclampsia and macrosomia. GDM is conventionally diagnosed by an oral glucose tolerance test (OGTT). Hemoglobin A1c (HbA1c) is a marker for the average glucose level the last 2-3 months. We aimed to study if HbA1c alone or in combination with patient characteristics can be used to screen for GDM and reduce the number of OGTTs, and whether it could predict preeclampsia or birth weight.

METHODS

855 women from a previous study on the effect of exercise on GDM prevalence were eligible, whereof 677 were included. GDM was diagnosed by WHO 1999 criteria (GDM-WHO) and modified IADPSG criteria (GDM-IADPSG), at pregnancy weeks 18-22 and 32-36. HbA1c analyzed at pregnancy weeks 18-22 and 32-36, variables from patient history and clinical examination were considered for logistic regression models. The diagnostic accuracy was assessed by ROC curve analysis.

RESULTS

Accumulated GDM prevalence was 6.7 % by WHO and 7.2 % by modified IADPSG criteria. Nearly a third could potentially have avoided an OGTT by using HbA1c to exclude GDM-IADPSG with a sensitivity of 88 % at week 18-22 and 97 % at week 32-36. Further, 16 % could have avoided an OGTT with a sensitivity of 96 % using HbA1c at week 18-22 to exclude GDM-IADPSG throughout pregnancy. HbA1c was not accurate at diagnosing GDM-IADPSG, and it was inaccurate at screening for GDM-WHO at any time point. Adding other predictors did not increase the number of potentially avoidable OGTTs significantly. HbA1c was not significantly associated with preeclampsia or birth weight.

CONCLUSIONS

HbA1c could potentially reduce the number of OGTTs.

Exercise Improves Glucose Disposal and Insulin Signaling in Pregnant Mice Fed a High Fat Diet

OBJECTIVE

Physical activity has been suggested as a non-pharmacological intervention that can be used to improve glucose homeostasis in women with gestational diabetes mellitus. The purpose of this study was to determine the effects of voluntary exercise on glucose tolerance and body composition in pregnant high fat diet fed mice.

METHODS

Female mice were put on a standard diet or high fat diet for two weeks. The mice were then split into 4 groups; control standard diet fed, exercise standard diet fed, control high fat diet fed, and exercise high fat diet fed. Exercise mice had voluntary access to a running wheel in their home cage one week prior to mating, during mating, and throughout pregnancy. Glucose tolerance and body composition were measured during pregnancy. Akt levels were quantified in skeletal muscle and adipose tissue isolated from saline or insulin injected pregnant dams as a marker for insulin signaling.

RESULTS

Consumption of the high fat diet led to significantly increased body weight, fat mass, and impaired glucose tolerance in control mice. However, voluntary running in the high fat diet fed dams significantly reduced weight gain and fat mass and ultimately improved glucose tolerance compared to control high fat diet fed dams. Further, body weight, fat mass, and glucose disposal in exercise high fat diet dams were indistinguishable from control dams fed the standard diet. High fat diet fed exercise dams also had significantly increased insulin stimulated phosphorylated Akt expression in adipose tissue, but not skeletal muscle, compared to control dams on high fat diet.

CONCLUSION

The use of voluntary exercise improves glucose homeostasis and body composition in pregnant female mice. Thus, future studies could investigate potential long-term health benefits in offspring born to obese exercising dams.

Prevention of gestational diabetes mellitus: Where are we now?

Gestational diabetes mellitus (GDM) is increasing at a rapid rate, driven by the increasing proportion of the population that is overweight/obese from a young age. More than 25 randomized controlled trials testing whether GDM can be prevented have now reported their findings, but only four different interventions have shown a reduction in the proportion of women with GDM (healthy eating alone, healthy eating with physical activity, myoinositol supplementation and probiotic treatment), and these results have not been replicated. The interventions tested to date include different diets and different forms of physical activity, in combination or alone, vitamin D, myoinositol, probiotics and metformin. Studies could be improved by using the International Association of Diabetes and Pregnancy Study Group criteria for GDM (which are probably more sensitive to change because of their multiple time points), targeting and tailoring interventions to subgroups most likely to benefit, and separating those with GDM early in pregnancy from those developing GDM de novo. The greatest societal benefit is likely to arise from population-based lifestyle approaches which include those women yet to become pregnant and those who are already pregnant and their families; an approach that is yet to be fully tested.

Targeting pregnancy as a time to treat obesity

Maternal obesity is recognized as one of the largest contributors to compromised health during pregnancy. Lifestyle interventions in obese pregnant women may be able to reduce gestational weight gain (GWG) but have shown limited success in improving pregnancy and neonatal outcomes. Lack of statistical power, poor compliance and inconsistency in inclusion BMI and setting across studies may be some of the reasons. Since pregestational BMI is the single most important predictor of obesity-related complications, the metabolic profile in the first trimester of pregnancy may play a very important role. Observational studies have shown that interpregnancy weight loss reduces the risk of macrosomia in a subsequent pregnancy. Future lifestyle randomized controlled trials should target the prepregnant state and examine the effect on maternal and neonatal outcomes.

Exercise guidelines for gestational diabetes mellitus

The prevalence of gestational diabetes mellitus (GDM) is increasing worldwide. This disease has many detrimental consequences for the woman, the unborn foetus and child. The management of GDM aims to mediate the effects of hyperglycaemia by controlling blood glucose levels. Along with pharmacology and dietary interventions, exercise has a powerful potential to assist with blood glucose control. Due to the uncertainty of risks and benefits of exercise during pregnancy, women tend to avoid exercise. However, under adequate supervision exercise is both safe and beneficial in the treatment of GDM. Therefore it is vital that exercise is incorporated into the continuum of care for women with GDM. Medical doctors should be able to refer to competently informed exercise professionals to aid in GDM treatment. It is important that exercise treatment is informed by research. Hence, the development of evidence-based guidelines is important to inform practice. Currently there are no guidelines for exercise in GDM. This review aims to assess the efficacy of exercise for the management of GDM in order to establish an exercise prescription guideline specific to the condition. It is recommended that women with GDM should do both aerobic and resistance exercise at a moderate intensity, a minimum of three times a week for 30-60 min each time.

Effect of an exercise intervention on gestational diabetes mellitus: a randomized controlled trial

OBJECTIVE

To examine the effect of an individually tailored, motivationally matched prenatal exercise intervention on gestational diabetes mellitus (GDM) and other measures of glucose intolerance among ethnically diverse prenatal care patients at increased risk for GDM.

METHODS

The Behaviors Affecting Baby and You study randomized eligible women at a mean (standard deviation) of 18.2 (4.1) weeks of gestation to a 12-week individually tailored, motivationally matched exercise intervention or a comparison health and wellness intervention. The goal of the exercise intervention was to achieve the American College of Obstetricians and Gynecologists' guidelines for physical activity during pregnancy. Diagnosis of GDM, impaired glucose tolerance, abnormal glucose screen, and screening glucose values (mg/dL) were abstracted from medical records. A sample size of 352 women (176 per group) was planned to have 80% power to detect reductions in risk of 35% or larger.

RESULTS

From July 2007 to December 2012, a total of 251 (86.5%) women completed the intervention; n=124 and 127 in the exercise and comparison interventions, respectively. Based on an intention-to-treat analysis, no statistically significant differences between the intervention groups were observed; the relative odds of GDM in the exercise group was 0.61 (95% confidence interval [CI] 0.28-1.32) as compared with the health and wellness comparison group. Odds ratios for impaired glucose tolerance and abnormal glucose screen were 0.68 (95% CI 0.35-1.34) and 0.86 (95% CI 0.51-1.47), respectively. The intervention had no effect on birth outcomes.

CONCLUSION

In this randomized trial among ethnically diverse pregnant women at increased risk for GDM, we found that a prenatal exercise intervention implemented in the second trimester did not result in a statistically significant reduction in relative odds for GDM, impaired glucose tolerance, or abnormal glucose screen.

LEVEL OF EVIDENCE

I.

Diet or exercise, or both, for preventing excessive weight gain in pregnancy

BACKGROUND

This is an update of a Cochrane review first published in 2012, Issue 4. Excessive weight gain during pregnancy is associated with poor maternal and neonatal outcomes including gestational diabetes, hypertension, caesarean section, macrosomia, and stillbirth. Diet or exercise interventions, or both, may reduce excessive gestational weight gain (GWG) and associated poor outcomes; however, evidence from the original review was inconclusive.

OBJECTIVES

To evaluate the effectiveness of diet or exercise, or both, interventions for preventing excessive weight gain during pregnancy and associated pregnancy complications.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (5 November 2014), contacted investigators of the previously identified ongoing studies and scanned reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of diet or exercise, or both, interventions for preventing excessive weight gain in pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We organised RCTs according to the type of interventions and pooled data using the random-effects model in the Review Manager software. We also performed subgroup analyses according to the initial risk of adverse effects related to poor weight control. We performed sensitivity analysis to assess the robustness of the findings.

MAIN RESULTS

We included 65 RCTs, out of which 49 RCTs involving 11,444 women contributed data to quantitative meta-analysis. Twenty studies were at moderate-to-high risk of bias. Study interventions involved mainly diet only, exercise only, and combined diet and exercise interventions, usually compared with standard care. Study methods varied widely; therefore, we estimated the average effect across studies and performed sensitivity analysis, where appropriate, by excluding outliers and studies at high risk of bias.Diet or exercise, or both, interventions reduced the risk of excessive GWG on average by 20% overall (average risk ratio (RR) 0.80, 95% confidence interval (CI) 0.73 to 0.87; participants = 7096; studies = 24; I² = 52%). This estimate was robust to sensitivity analysis, which reduced heterogeneity, therefore we graded this evidence as high-quality. Interventions involving low glycaemic load diets, supervised or unsupervised exercise only, or diet and exercise combined all led to similar reductions in the number of women gaining excessive weight in pregnancy.Women receiving diet or exercise, or both interventions were more likely to experience low GWG than those in control groups (average RR 1.14, 95% CI 1.02 to 1.27; participants = 4422; studies = 11; I² = 3%; moderate-quality evidence). We found no difference between intervention and control groups with regard to pre-eclampsia (RR 0.95, 95% CI 0.77 to 1.16; participants = 5330; studies = 15; I² = 0%; high-quality evidence); however, maternal hypertension (not a pre-specified outcome) was reduced in the intervention group compared with the control group overall (average RR 0.70, 95% CI 0.51 to 0.96; participants = 5162; studies = 11; I² = 43%; low-quality evidence).There was no clear difference between groups with regard to caesarean delivery overall (RR 0.95, 95% CI 0.88 to 1.03; participants = 7534; studies = 28; I² = 9%; high-quality evidence); although the effect estimate suggested a small difference (5%) in favour of the interventions. In addition, for combined diet and exercise counselling interventions there was a 13% (-1% to 25%) reduction in this outcome (borderline statistical significance).We found no difference between groups with regard to preterm birth overall (average RR 0.91, 95% CI 0.68 to 1.22; participants = 5923; studies = 16; I² = 16%; moderate-quality evidence); however limited evidence suggested that these effect estimates may differ according to the types of interventions, with a trend towards an increased risk for exercise-only interventions.We found no clear difference between intervention and control groups with regard to infant macrosomia (average RR 0.93, 95% CI 0.86 to 1.02; participants = 8598; studies = 27; I² = 0%; high-quality evidence), although the effect estimate suggested a small difference (7% reduction) in favour of the intervention group. The largest effect size occurred in the supervised exercise-only intervention group (RR 0.81, 95% CI 0.64 to 1.02; participants = 2445; studies = 7; I² = 0%), which approached statistical significance (P = 0.07). Furthermore, in subgroup analysis by risk, high-risk women (overweight or obese women, or women with or at risk of gestational diabetes) receiving combined diet and exercise counselling interventions experienced a 15% reduced risk of infant macrosomia (average RR 0.85, 95% CI 0.73 to 1.00; participants = 3252; studies = nine; I² = 0; P = 0.05; moderate-quality evidence)There were no differences in the risk of poor neonatal outcomes including shoulder dystocia, neonatal hypoglycaemia, hyperbilirubinaemia, or birth trauma (all moderate-quality evidence) between intervention and control groups; however, infants of high-risk women had a reduced risk of respiratory distress syndrome if their mothers were in the intervention group (RR 0.47, 95% CI 0.26 to 0.85; participants = 2256; studies = two; I² = 0%; moderate-quality evidence).

AUTHORS' CONCLUSIONS

High-quality evidence indicates that diet or exercise, or both, during pregnancy can reduce the risk of excessive GWG. Other benefits may include a lower risk of caesarean delivery, macrosomia, and neonatal respiratory morbidity, particularly for high-risk women receiving combined diet and exercise interventions. Maternal hypertension may also be reduced. Exercise appears to be an important part of controlling weight gain in pregnancy and more research is needed to establish safe guidelines. Most included studies were carried out in developed countries and it is not clear whether these results are widely applicable to lower income settings.

Physical activity interventions in pregnancy and risk of gestational diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

Gestational diabetes mellitus (GDM) is a common complication of pregnancy associated with an increased incidence of pregnancy complications, adverse pregnancy outcomes, and maternal and fetal risks of chronic health conditions later in life. Physical activity has been proposed to reduce the risk of GDM and is supported by observational studies, but experimental research assessing its effectiveness is limited and conflicting. We aimed to use meta-analysis to synthesize existing randomized controlled studies of physical activity and GDM.

DATA SOURCES

We searched MEDLINE, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for eligible studies.

METHODS OF STUDY SELECTION

The following combination of keywords was used: (pregnant or pregnancy or gestation or gestate or gestational or maternity or maternal or prenatal) AND (exercise or locomotion or activity or training or sports) AND (diabetes or insulin sensitivity or glucose tolerance) AND (random* or trial). Eligibility was restricted to studies that randomized participants to an exercise-only-based intervention (ie, separate from dietary interventions) and presented data regarding GDM risk. Two authors performed the database search, assessment of eligibility, and abstraction of data from included studies, and a third resolved any discrepancies. A total of 469 studies was retrieved, of which 10 met inclusion criteria and could be used for analysis (3,401 participants).

TABULATION, INTEGRATION, AND RESULTS

Fixed-effects models were used to estimate summary relative risk (RR) and 95% confidence interval (CI) and I to assess heterogeneity. There was a 28% reduced risk (95% CI 9-42%) in the intervention group compared with the control group (RR 0.72, P=.005). Heterogeneity was low (I=12%) and nonsignificant (P=.33).

CONCLUSION

The results from this meta-analysis suggest that physical activity in pregnancy provides a slight protective effect against the development of GDM. Studies evaluating type, timing, duration, and compliance of physical activity regimens are warranted to best inform obstetric guidelines.

Update on Prepregnancy Maternal Obesity: Birth Defects and Childhood Outcomes

Obesity is a growing global health epidemic. It is estimated that more than 20% of pregnancies are complicated by obesity. Prepregnancy obesity has been associated with birth defects such as neural tube defects, macrosomia, fetal death, and long-term effects such as asthma on the offspring. We provide a summary of the most recent studies and meta-analyses on obesity and birth outcome. Possible mechanisms of actions are explored and recommendations for further research are highlighted.

Regular moderate exercise during pregnancy does not have an adverse effect on the neurodevelopment of the child

AIM

Current U.S. guidelines suggest that pregnant women should exercise regularly during pregnancy, and we examined the neurodevelopment of the children whose mothers had taken that advice.

METHODS

This Norwegian study included 188 children whose mothers had followed a structured exercise protocol and 148 control children whose mothers had not. Their cognitive, language and motor skills were assessed at 18 months of age by the Bayley Scales of Infant Development-III and daily life functioning with the Ages and Stages Questionnaire.

RESULTS

No significant differences were found between the two groups. Subgroup analyses revealed that the children whose mothers had exercised had a slightly lower motor composite score (mean: 97.6, 95% CI: 96.0-99.2) than the control group (mean: 100.0, 95% CI: 98.6-101.5) (p = 0.03). Boys in the intervention group had lower fine motor scores (mean: 10.6, 95% CI: 10.3-11.0) than boys in the control group (mean: 11.5, 95% CI: 11.0-11.9) (p = 0.01).

CONCLUSION

Our main finding was that regular moderate exercise during pregnancy does not adversely affect neurodevelopment in children. The lower motor scores in the subgroup analyses are probably clinically insignificant, but the lower fine motor scores for boys in the intervention group warrant further research.

Association between physical activity in obese pregnant women and pregnancy outcomes: the UPBEAT pilot study

BACKGROUND

Obesity in pregnancy is associated with fetal macrosomia, a raised neonatal fat mass and an increased risk of obesity and poor metabolic health in childhood which persists into adulthood. The offspring of obese women are more likely to be obese than the offspring of lean women when they become pregnant themselves, perpetuating a cycle of obesity and its associated negative metabolic consequences. Increasing physical activity during pregnancy could improve insulin sensitivity and reduce the risk of maternal and offspring adverse outcomes. The UK Pregnancy Better Eating and Activity Trial (UPBEAT) is a trial of a complex intervention designed to improve pregnancy outcomes through dietary changes and physical activity. Data from the pilot trial of 183 women were available for analysis. The relationship between the time spent at different physical activity levels and maternal and infant pregnancy outcomes was examined.

KEY MESSAGES

Strong evidence exists that physical activity improves insulin sensitivity in non-pregnant populations, and lifestyle interventions of proven effectiveness in non-pregnant populations have been developed. Women who are active in pregnancy demonstrate better glucose control and favourable pregnancy outcomes. There is a lack of effective interventions to support obese pregnant women to be physically active.

CONCLUSIONS

No difference was detected in objectively measured physical activity between women randomised to the intervention and control arms of the UPBEAT pilot trial. Light-intensity physical activity was lower in early pregnancy in women who delivered macrosomic infants. Maternal sedentary time at 35-36 weeks' gestation was positively associated and moderate-intensity physical activity was inversely associated with neonatal abdominal circumference. Maternal physical activity is associated with infant birth weight and abdominal circumference and is an appropriate target for intervention to improve infant outcomes. The challenge remains to develop an effective intervention to support obese pregnant women to be physically active.

Effect of physical activity during pregnancy on mode of delivery

OBJECTIVE

The purpose of this study was to evaluate the effect of structured physical exercise programs during pregnancy on the course of labor and delivery.

STUDY DESIGN

We conducted a systematic review and metaanalysis using the following data sources: Medline and The Cochrane Library. In our study, we used randomized controlled trials (RCT) that evaluated the effects of exercise programs during pregnancy on labor and delivery. The results are summarized as relative risks.

RESULTS

In the 16 RCTs that were included there were 3359 women. Women in exercise groups had a significantly lower risk of cesarean delivery (relative risk, 0.85; 95% confidence interval [CI], 0.73-0.99). Birthweight was not significantly reduced in exercise groups. The risk of instrumental delivery was similar among groups (relative risk, 1.00; 95% CI, 0.82-1.22). Data on Apgar score, episiotomy, epidural anesthesia, perineal tear, length of labor, and induction of labor were insufficient to draw conclusions. With the use of data from 11 studies (1668 women), our analysis showed that women in the exercise groups gained significantly less weight than women in control groups (mean difference, -1.13 kg; 95% CI, -1.49 to -0.78).

CONCLUSION

Structured physical exercise during pregnancy reduces the risk of cesarean delivery. This is an important finding to convince women to be active during their pregnancy and should lead the physician to recommend physical exercise to pregnant women, when this is not contraindicated.

The effect of exercise and metformin treatment on circulating free DNA in pregnancy

INTRODUCTION

Some pregnancy complications are characterized by increased levels of cell-free fetal (cffDNA) and maternal DNA (cfmDNA), the latter may also be elevated during physical strain. This study aims at assessing the impact of exercise and metformin intervention in pregnancy, and to compare the levels of cell free DNA in pregnant women with or without PCOS diagnosis.

METHODS

Consecutive women from two previous randomized controlled trials in pregnancy were included. Women came from a trial with organized exercise vs. standard antenatal care in pregnancy and a trial of metformin vs. placebo in PCOS women. Levels of cffDNA, cfmDNA and cell-free total DNA (cftDNA) were measured by qPCR.

RESULTS

Training in pregnancy did not affect the levels of cffDNA, cfmDNA or cftDNA. PCOS-women treated with metformin had lower levels of cfmDNA and cftDNA at week 32 (mean ± SD: 301 ± 162 versus 570 ± 337, p = 0.012, 345 ± 173 versus 635 ± 370, p = 0.019); otherwise the levels were comparable to PCOS-controls. Metformin-treated PCOS-women had higher cffDNA at inclusion, in the 1st trimester; later on in pregnancy the levels in the metformin and placebo groups were equal. A comparison of pregnant women in the exercise study (TRIP) to placebo-treated pregnant PCOS-women, showed the levels of cffDNA, cfmDNA or cftDNA during mid-pregnancy (weeks 18-36) to be equal.

DISCUSSION

Training during pregnancy was not associated with altered levels of cffDNA cfmDNA or cftDNA, but metformin treatment may reduce cfmDNA and cftDNA in pregnant PCOS women.

Gestational diabetes mellitus among Nordic Caucasian women: prevalence and risk factors according to WHO and simplified IADPSG criteria

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with both maternal and offspring adverse effects. The World Health Organization (WHO) has recently adopted novel GDM criteria. The aim of this study was to evaluate the former WHO and a simplified version of the new International Association for Diabetes in Pregnancy Study Group (IADPSG) criteria as to prevalence of and risk factors for GDM in a Nordic Caucasian population.

METHODS

A 75 g oral glucose tolerance test was performed in 687 women at 18-22 and 32-36 pregnancy weeks. GDM was defined according to the WHO criteria as fasting plasma glucose ≥ 7.0 mmol/L and/or 2-hour plasma glucose ≥ 7.8 mmol/L and by a simplified version of the IADPSG criteria as either fasting glucose ≥ 5.1 mmol/L and/or 2-h plasma glucose ≥ 8.5 mmol/L. One-hour glucose values were not available and were thus not included in the diagnosis of GDM by IADPSG. Prevalence of GDM during pregnancy and risk factors for GDM at 18-22 weeks were studied in retrospect according to each of the two criteria.

RESULTS

The total prevalence of GDM during pregnancy was 6.1% (42/687) for the WHO criteria and 7.4% (51/687) for the simplified IADPSG criteria. High maternal age and short stature were independently associated with WHO GDM. Maternal age, fasting insulin and no regular exercise at 18-22 pregnancy weeks associated with simplified IADPSG GDM.

CONCLUSIONS

Simplified IADPSG criteria moderately increase GDM prevalence compared with the WHO criteria. Risk factors for GDM differ with the diagnostic criteria used.

Population health: modest glycaemic improvements in a pregnant cohort with mild glucose intolerance decreased adverse outcomes

BACKGROUND

Adverse perinatal outcomes are common with pregnancy-related mild glucose intolerance. The perinatal impact of improving this population's health, instead of individual health, has not been quantified.

METHODS

We estimated this impact among women with mild glucose intolerance, delivered at The University of North Carolina Women's Hospital from April 1996 to May 2010. We compared observed with predicted risks of perinatal outcomes after simulating a cohort with a one standard deviation decrease in each glucose value. We estimated absolute and adjusted risks, relative risks, and risk differences with Poisson regression and bootstrapped 95% confidence intervals [CI].

RESULTS

Among 3217 women, mean (SD) 1-h screening result was 157 (16) mg/dL; 3-h diagnostic results were 81 (10), 154 (28), 130 (25), and 104 (26) mg/dL for fasting, 1-h, 2-h, and 3-h, respectively. Compared with observed, predicted risks decreased for preeclampsia (9.1% vs. 6.6%, risk ratio [RR] 0.73 [95% CI 0.60, 0.88]), caesarean delivery (30.1% vs. 26.4%, RR 0.88 [95% CI 0.81, 0.96]), preterm birth (13.0% vs. 9.8%, RR 0.75 [95% CI 0.64, 0.87]), birthweight >4000 g (13.4% vs. 10.5%, RR 0.78 [95% CI 0.67, 0.90]), and shoulder dystocia (3.5% vs. 2.2%, RR 0.61 [95% CI 0.46, 0.83]).

CONCLUSIONS

Modestly improved population distribution of glucose tolerance in pregnancies affected by mild glucose intolerance translated to meaningful improvements in perinatal outcomes.

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.

Behavior modification techniques used to prevent gestational diabetes: a systematic review of the literature

The prevalence of gestational diabetes mellitus (GDM) and obesity is increasing in developed countries, presenting significant challenges to acute care and public health. The aim of this study is to systematically review published controlled trials evaluating behavior modification interventions to prevent the development of GDM. Nine studies were identified involving such techniques as repetition of information, use of verbal and written educational information, goal setting, and planning, in addition to group and individual counseling sessions. Of the 3 trials with GDM incidence as a primary outcome, only 1 showed a significant reduction. GDM was a secondary outcome in 6 studies where the prevention of excessive gestational weight gain was the primary outcome and only 1 trial study determined an effective intervention. The small number of effective interventions highlights a significant gap in evidence to inform maternity health policy and practice.

Objectively recorded physical activity and the association with gestational diabetes

The aim of this population-based study was to assess the association between objectively recorded physical activity (PA) in early gestation and gestational diabetes mellitus (GDM) identified at 28 weeks of gestation in a multi-ethnic cohort of healthy pregnant women in Oslo, Norway. In total, 759 women were included. In early gestation (<20 weeks), light-, moderate-, and vigorous-intensity PA and number of steps were objectively recorded (SenseWear™ Armband Pro3), and self-reported PA, demographics, and anthropometrics were collected. The 75-g oral glucose tolerance test was performed at 28 weeks of gestation. Women with GDM had fewer objectively recorded steps (mean 7964 steps/day vs 8879 steps/day, P < 0.001) and minutes of moderate-to-vigorous-intensity PA (median 62 min/day vs 75 min/day, P = 0.004) in early gestation than women without GDM. Additionally, 30% of women with GDM compared with 44% (P < 0.001) of women without GDM self-reported regular PA before pregnancy. The significant inverse association between objectively recorded steps per day in early gestation and GDM persisted after adjustment for ethnic origin, weeks of gestation, age, parity, pre-pregnancy BMI, early life socioeconomic position, and self-reported regular PA before pregnancy. The adjusted odds ratio for GDM decreased 19% per standard deviation (3159 steps) increase in objectively recorded steps per day (P = 0.039). Daily life PA in early gestation measured as steps/day was associated with lower risk of GDM.

The role of lifestyle interventions in the prevention of gestational diabetes

Gestational diabetes is associated with adverse pregnancy outcomes, increased costs, and long-term risk of type 2 diabetes mellitus (T2DM) in the mother. Observational data have shown an association between reduced weight gain, healthy eating, and physical activity and reduced rates of gestational diabetes mellitus (GDM). Despite this, most randomized controlled trials of lifestyle interventions to prevent GDM have been negative. Dietary approaches appear to be more successful than exercise or a combination of diet and exercise at decreasing GDM. Reasons for negative studies may include lack of power, lack of intervention uptake, and severity of placenta mediated insulin resistance. Future studies should be powered for a reduction in GDM, monitor lifestyle changes closely, and include a psychological component in the intervention.

Physical activity during pregnancy and the risk of gestational diabetes mellitus: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVES

We performed a systematic review and meta-analysis to assess the effects of physical activity in preventing gestational diabetes mellitus (GDM).

SEARCH STRATEGY

We searched the literature in six electronic databases and bibliographies of relevant articles.

SELECTION CRITERIA

We included randomised controlled trials on pregnant women who did not have GDM and other complications previously and had increased physical activity as the only intervention. The risk of developing GDM was documented separately for the intervention and control groups.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data and assessed quality independently. Data from the included trials were combined using a fixed-effects model. The effect size was expressed as relative risk (RR) and 95% CI.

MAIN RESULTS

Of the 1110 studies identified, six randomised controlled trials met the inclusion criteria. In three trials, the incidence of GDM was lower in the intervention group than in the control group, whereas two trials showed a higher incidence of GDM in the intervention group and the remaining trial found no GDM in either the intervention or control group. The meta-analysis resulted in a relative risk (RR) of GDM of 0.91 (95% CI 0.57 to 1.44), suggesting no significant difference in the risk of developing GDM between the intervention and the control groups. No indication of publication bias was found.

CONCLUSIONS

Evidence was insufficient to suggest that physical activity during pregnancy might be effective to lower the risk of developing GDM.

The important role of physical activity in the prevention and management of gestational diabetes mellitus

The actual pathophysiology behind gestational diabetes mellitus (GDM) is still unclear, but a deterioration in insulin resistance beyond that induced by pregnancy, combined with beta cell dysfunction, plays a key role. Interventions that help improve glucose tolerance by attenuating pregnancy-induced insulin resistance or achieve glycaemic control may therefore help in preventing and managing GDM. In non-pregnant populations, physical activity has been associated with an improvement in glucose homeostasis and insulin sensitivity and a risk reduction for type 2 diabetes mellitus (T2DM) and is a cornerstone for T2DM treatment. However, there is still controversy regarding the benefits of physical activity in preventing and managing GDM. The objective of this review is therefore to provide a comprehensive overview of the effect of prenatal physical activity-based interventions on (1) glucose tolerance, insulin sensitivity and GDM prevention and (2) glycaemic control and insulin use in GDM women. On the basis of the available literature, there is a lack of consistent evidence regarding the benefits of physical activity on improving glucose tolerance and insulin sensitivity and preventing GDM. However, it appears that physical activity may help to achieve good glycaemic control and limit insulin use in GDM women. Compliance appears to be a major problem in physical activity-based intervention studies aimed at GDM prevention. Rigorous scientific research is still required to make an informed decision about the role of physical activity in the prevention and management of GDM and to develop evidence-based physical activity guidelines for GDM prevention and management.

Benefits of exercise during pregnancy

There is a direct link between healthy mothers and healthy infants. Exercise and appropriate nutrition are important contributors to maternal physical and psychological health. The benefits and potential risks of exercise during pregnancy have gained even more attention, with a number of studies having been published after the 2002 American College of Obstetrics and Gynecologists guidelines. A review of the literature was conducted by using PubMed, Scopus, and Embase to assess the literature regarding the benefits of exercise during pregnancy. The search revealed 219 publications, which the authors then narrowed to 125 publications. The purpose of this review is to briefly summarize the known benefits of exercise to the mother, fetus, and newborn.

Primary prevention of gestational diabetes for women who are overweight and obese: a randomised controlled trial

BACKGROUND

Gestational Diabetes Mellitus (GDM) has well recognised adverse health implications for the mother and her newborn that are both short and long term. Obesity is a significant risk factor for developing GDM and the prevalence of obesity is increasing globally. It is a matter of public health importance that clinicians have evidence based strategies to inform practice and currently there is insufficient evidence regarding the impact of dietary and lifestyle interventions on improving maternal and newborn outcomes. The primary aim of this study is to measure the impact of a telephone based intervention that promotes positive lifestyle modifications on the incidence of GDM. Secondary aims include: the impact on gestational weight gain; large for gestational age babies; differences in blood glucose levels taken at the Oral Glucose Tolerance Test (OGTT) and selected factors relating to self-efficacy and psychological wellbeing.

METHOD/DESIGN

A randomised controlled trial (RCT) will be conducted involving pregnant women who are overweight (BMI >25 to 29.9 k/gm2) or obese (BMI >30 kgm/2), less than 14 weeks gestation and recruited from the Barwon South West region of Victoria, Australia. From recruitment until birth, women in the intervention group will receive a program informed by the Theory of Self-efficacy and employing Motivational Interviewing. Brief ( less than 5 minute) phone contact will alternate with a text message/email and will involve goal setting, behaviour change reinforcement with weekly weighing and charting, and the provision of health information. Those in the control group will receive usual care. Data for primary and secondary outcomes will be collected from medical record review and a questionnaire at 36 weeks gestation.

DISCUSSION

Evidence based strategies that reduce the incidence of GDM are a priority for contemporary maternity care. Changing health behaviours is a complex undertaking and trialling a composite intervention that can be adopted in various primary health settings is required so women can be accessed as early in pregnancy as possible. Using a sound theoretical base to inform such an intervention will add depth to our understanding of this approach and to the interpretation of results, contributing to the evidence base for practice and policy.

TRIAL REGISTRATION

This trial is registered with the Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12613000125729.

Different fatty acid pattern in breast milk of obese compared to normal-weight mothers

INTRODUCTION

The aim of this study was to investigate the fatty acid (FA) pattern in breast milk of obese mothers and their neonates' plasma compared to those of normal weight mothers.

PATIENTS AND METHODS

This was an observational study of 41 obese and 41 normal weight pregnant women. Twenty-nine obese women participating in a weight reduction program were investigated for comparison. FAs were analyzed in breast milk collected at 3 and 10 days and one and two months postnatally and in infant's plasma 3 days after birth.

RESULTS AND CONCLUSIONS

The concentration of long-chain n-3 FA were lower and the ratio n-6/n-3 FA higher in neonates and in consecutive samples of breast milk of obese mothers compared to normal weight mothers. The obese mothers that participated in an intervention program with general dietary advice had FA concentrations approaching that of the normal-weight mothers. The study indicates importance of dietary advice in pregnancy.

Effect of intensive counselling on physical activity in pregnant women at high risk for gestational diabetes mellitus. A clinical study in primary care

OBJECTIVE

The level of physical activity (PA) of pregnant women in Finland is unknown. Even more limited is our knowledge of PA of women at high risk for gestational diabetes mellitus (GDM).

METHODS

The women (n=54) were randomly assigned to a lifestyle intervention group (n=27) including exercise advice by a physiotherapist six times during pregnancy or to a control group (n=27) without additional exercise advice. Outcomes of the present study were required sample size, timing of counselling and change of PA. PA was retrospectively reported during 12 months before pregnancy and recorded one week monthly during pregnancy.

RESULTS

Individualized counselling by a physiotherapist resulted in small changes of recreational PA (2.7 MET hours/week, p=0.056) up to gestational week 25 compared with the similar decreasing tendency of PA in the control group. The women decreased recreational PA after week 30. Sample size of 550 women at high risk for GDM per group would be needed for a PA study.

CONCLUSIONS

The optimal time window for increasing PA must be earlier than in the last trimester of pregnancy. Sample size for a study to increase PA by 2.7 MET hours/week on pregnant women at high risk of GDM should be about 550 per group.