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

The Effect of Gestational Diabetes Mellitus on Hearing of Neonates in a Tertiary Healthcare Centre

Congenital hearing loss is hearing loss present in a child at birth or soon after birth. It is a debilitating condition with the potential for lifelong disability. It is thought to be multifactorial in aetiology with both genetic (autosomal and X-linked) and acquired causes (such as maternal infections, drug intake, trauma). Gestational Diabetes Mellitus (GDM) is a relatively common condition found in pregnant females but is a rather understudied risk factor in terms of congenital hearing loss. GDM is easily treatable which makes the hearing loss due to it easily preventable. (1) Determine correlation between Gestational Diabetes Mellitus and congenital hearing loss in neonates. (2) Calculate the prevalence of Gestational Diabetes Mellitus related congenital hearing loss. A two-step screening process was used for hearing evaluation of neonates with normal mothers (non-exposed) and neonates with mothers suffering from GDM (exposed) through Otoacoustic emission (OAE) and Brainstem Evoked Response Audiometry (BERA). (1) The difference of neonates diagnosed with hearing impairment in exposed and non-exposed group was statistically significant with a p-value of 0.024. OR 2.1538 95% CI 0.6120-7.5796, p < 0.05. (2) Prevalence of hearing loss in neonates of GDM mothers: 13.3%. Through rigorous exclusion of the already known risk factors for congenital hearing loss, Gestational Diabetes Mellitus has been isolated as an independent risk factor for neonatal hearing impairment. We hope to identify additional cases of congenital hearing loss early leading to a decrease in disease burden.

Combined diet and exercise interventions for preventing gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a wide range of adverse health consequences for women and their infants in the short and long term. With an increasing prevalence of GDM worldwide, there is an urgent need to assess strategies for GDM prevention, such as combined diet and exercise interventions. This is an update of a Cochrane review that was first published in 2015.

OBJECTIVES

To assess the effects of diet interventions in combination with exercise interventions for pregnant women for preventing GDM, and associated adverse health consequences for the mother and her infant/child.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 November 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and cluster-RCTs, comparing combined diet and exercise interventions with no intervention (i.e. standard care), that reported on GDM diagnosis as an outcome. Quasi-RCTs were excluded. Cross-over trials were not eligible for inclusion. We planned to include RCTs comparing two or more different diet/exercise interventions, however none were identified.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data, assessed the risk of bias of the included trials and assessed quality of evidence for selected maternal and infant/child outcomes using the GRADE approach. We checked data for accuracy.

MAIN RESULTS

In this update, we included 23 RCTs (involving 8918 women and 8709 infants) that compared combined diet and exercise interventions with no intervention (standard care). The studies varied in the diet and exercise programs evaluated and health outcomes reported. None reported receiving funding from a drug manufacturer or agency with interests in the results. Overall risk of bias was judged to be unclear due to the lack of methodological detail reported. Most studies were undertaken in high-income countries.For our primary review outcomes, there was a possible reduced risk of GDM in the diet and exercise intervention group compared with the standard care group (average risk ratio (RR) 0.85, 95% confidence interval (CI) 0.71 to 1.01; 6633 women; 19 RCTs; Tau² = 0.05; I² = 42%; P = 0.07; moderate-quality evidence). There was also a possible reduced risk of caesarean section (RR 0.95, 95% CI 0.88 to 1.02; 6089 women; 14 RCTs; moderate-quality evidence). No clear differences were seen between groups for pre-eclampsia (RR 0.98, 95% CI 0.79 to 1.22; 5366 participants; 8 RCTs; low-quality evidence), pregnancy-induced hypertension and/or hypertension (average RR 0.78, 95% CI 0.47 to 1.27; 3073 participants; 6 RCTs; Tau² = 0.19; I² = 62%; very low-quality evidence), perinatal mortality (RR 0.82, 95% CI 0.42 to 1.63; 3757 participants; 2 RCTs; low-quality evidence) or large-for-gestational age (RR 0.93, 95% CI 0.81 to 1.07; 5353 participants; 11 RCTs; low-quality evidence). No data were reported for infant mortality or morbidity composite.Subgroup analyses (based on trial design, maternal body mass index (BMI) and ethnicity) revealed no clear differential treatment effects. We were unable to assess the impact of maternal age, parity and specific features of the diet and exercise interventions. Findings from sensitivity analyses (based on RCT quality) generally supported those observed in the main analyses. We were not able to perform subgroup analyses based on maternal age, parity or nature of the exercise/dietary interventions due to the paucity of information/data on these characteristics and the inability to meaningfully group intervention characteristics.For most of the secondary review outcomes assessed using GRADE, there were no clear differences between groups, including for perineal trauma (RR 1.27, 95% CI 0.78 to 2.05; 2733 participants; 2 RCTs; moderate-quality evidence), neonatal hypoglycaemia (average RR 1.42, 95% CI 0.67 to 2.98; 3653 participants; 2 RCTs; Tau² = 0.23; I² = 77%; low quality evidence); and childhood adiposity (BMI z score) (MD 0.05, 95% CI -0.29 to 0.40; 794 participants; 2 RCTs; Tau² = 0.04; I² = 59%; low-quality evidence). However, there was evidence of less gestational weight gain in the diet and exercise intervention group compared with the control group (mean difference (MD) -0.89 kg, 95% CI -1.39 to -0.40; 5052 women; 16 RCTs; Tau² = 0.37; I² = 43%;moderate-quality evidence). No data were reported for maternal postnatal depression or type 2 diabetes; childhood/adulthood type 2 diabetes, or neurosensory disability.

AUTHORS' CONCLUSIONS

Moderate-quality evidence suggests reduced risks of GDM and caesarean section with combined diet and exercise interventions during pregnancy as well as reductions in gestational weight gain, compared with standard care. There were no clear differences in hypertensive disorders of pregnancy, perinatal mortality, large-for-gestational age, perineal trauma, neonatal hypoglycaemia, and childhood adiposity (moderate- tovery low-quality evidence).Using GRADE methodology, the evidence was assessed as moderate to very low quality. Downgrading decisions were predominantly due to design limitations (risk of bias), and imprecision (uncertain effect estimates, and at times, small sample sizes and low event rates), however two outcomes (pregnancy-induced hypertension/hypertension and neonatal hypoglycaemia), were also downgraded for unexplained inconsistency (statistical heterogeneity).Due to the variability of the diet and exercise components tested in the included studies, the evidence in this review has limited ability to inform practice. Future studies could describe the interventions used in more detail, if and how these influenced behaviour change and ideally be standardised between studies. Studies could also consider using existing core outcome sets to facilitate more standardised reporting.

Does gestational diabetes result in cochlear damage?

BACKGROUND

Glucose metabolism has a significant impact on inner-ear physiology. Therefore, hearing may be affected in gestational diabetes.

METHOD

A matched case-control study was performed to evaluate 27 patients with gestational diabetes and 31 non-diabetic pregnant women with similar demographic characteristics. A medical history was taken for each participant, and otological inspections and high-frequency audiometry tests were performed.

RESULTS

There were no significant differences in average pure tone air-bone hearing thresholds between the groups (p > 0.05). However, evaluation of high-frequency hearing thresholds indicated significantly increased auditory thresholds at 10 kHz and 12 kHz for right ears and at 8, 10, 12 and 14 kHz for left ears in the gestational diabetes group (p < 0.001).

CONCLUSION

An investigation into cochlear damage in gestational diabetic patients showed significant high-frequency hearing loss. Further studies are needed to validate these findings in different ethnic groups and geographical populations.

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.

Diet and exercise interventions for preventing gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a wide range of adverse health consequences for women and their babies in the short and long term. With an increasing prevalence of GDM worldwide, there is an urgent need to assess strategies for GDM prevention, such as combined diet and exercise interventions.

OBJECTIVES

To assess the effects of combined diet and exercise interventions for preventing GDM and associated adverse health consequences for women and their babies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (11 February 2014) and reference lists of retrieved studies. We updated the search in February 2015 but these results have not yet been incorporated and are awaiting classification.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and cluster-RCTs assessing the effects of interventions that included diet and exercise components. We included studies where combined diet and exercise interventions were compared with no intervention (i.e. standard care).We planned to also compare diet and exercise interventions with alternative diet and/or exercise interventions but no trials were identified for this comparison.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data and assessed the risk of bias of the included studies. Data were checked for accuracy.

MAIN RESULTS

We included 13 randomised controlled trials (involving 4983 women and their babies). We assessed the included trials as being of moderate risk of bias overall.When comparing women receiving a diet and exercise intervention with those receiving no intervention, there was no clear difference in the risk of developing GDM (average risk ratio (RR) 0.92, 95% confidence interval (CI) 0.68 to 1.23; 11 trials, 3744 women), caesarean section (RR 0.92, 95% CI 0.83 to 1.01; seven trials, 3246 women), or large-for-gestational age (RR 0.90, 95% CI 0.77 to 1.05; 2950 infants). Only one trial reported on perinatal mortality, and found no clear difference in the risk of stillbirth (RR 0.99, 95% CI 0.29 to 3.42; 2202 fetuses) or neonatal death (RR 0.99, 95% CI 0.06 to 15.85; 2202 neonates).Very few differences were shown between groups for the review's secondary outcomes, including for induction of labour, perineal trauma, pre-eclampsia, postpartum haemorrhage and infection, macrosomia, birthweight, small-for-gestational age, ponderal index, neonatal hypoglycaemia requiring treatment, hyperbilirubinaemia requiring treatment, shoulder dystocia, bone fracture or nerve palsy. Women receiving a combined diet and exercise intervention were, however, found to have a reduced risk of preterm birth compared with women receiving no intervention (RR 0.71, 95% CI 0.55 to 0.93; five trials, 2713 women).A trend towards reduced weight gain during pregnancy was shown for women receiving the combined diet and exercise intervention (mean difference (MD) -0.76 kg, 95% CI -1.55 to 0.03; eight trials, 2707 women; P = 0.06, random-effects); but no clear difference in postnatal weight retention was observed overall.In relation to adherence to the interventions, a number of trials that reported on behaviour modifications showed benefits in diet- (5/8 trials) and physical activity- (4/8 trials) related behaviours for women receiving the combined diet and exercise intervention, compared with women receiving no intervention; however there was notable variation across trials in outcomes measured and results observed. Only two trials reported on well-being and quality of life of women, and did not observe differences between groups for these outcomes.Very few trials reported on outcomes relating to the use of health services, although one trial suggested a reduced length of antenatal hospital stay for women receiving a combined diet and exercise intervention (MD -0.27 days, 95% CI -0.49 to -0.05; 2153 women).No information was available on outcomes for the infant as a child or adult, or for most longer-term outcomes for the mother.

AUTHORS' CONCLUSIONS

There are limitations associated with the available RCT evidence on the effects of combined diet and exercise interventions during pregnancy for preventing GDM. Results from 13 RCTs (of moderate quality) suggest no clear difference in the risk of developing GDM for women receiving a combined diet and exercise intervention compared with women receiving no intervention. However, the ability to draw firm conclusions was limited by variations in the quality of trials, characteristics of the interventions and populations assessed, and outcome definitions between trials.Based on the data currently available, conclusive evidence is not available to guide practice. Further large, well-designed RCTs, addressing the limitations of previous studies, are needed to assess the effects of combined interventions on preventing GDM and other relevant pregnancy outcomes including caesarean birth, large-for-gestational age and perinatal mortality. Health service utilisation and costs, and longer-term outcomes for mothers and their babies should be included. We identified another 16 trials which are ongoing and we will consider these for inclusion in the next update of this review.

Optimizing Weight for Maternal and Infant Health - Tenable, or Too Late?

Obesity in pregnancy is the leading cause of maternal and fetal morbidity, and gestational weight gain (GWG) is one modifiable risk factor that improves pregnancy outcomes. Most pregnant women gain more than the 2009 Institute of Medicine recommendations, particularly overweight and obese women. GWG even less than the 2009 IOM guidelines in obese women may improve pregnancy outcomes and reduce large-for-gestational-age (LGA) infants, an independent risk factor for childhood obesity, without increasing small-for-gestational-age (SGA) infants. Unfortunately, despite the fact that over 50 interventional trials designed to decrease excess GWG have been conducted, these interventions have been only modestly effective, and interventions designed to facilitate weight postpartum weight loss have also been disappointing. Successful interventions are of paramount importance not only to improve pregnancy outcomes but also for the future metabolic health of the mother and her infant, and may be key in attenuating the trans-generational risk on childhood obesity.