Metformin in pregnancy to avert gestational diabetes in women at high risk: Meta-analysis of randomized controlled trials

Metformin in gestational diabetes: physiological actions and clinical applications

Metformin is an effective oral hypoglycaemic agent used in the treatment of type 2 diabetes mellitus; however, its use in pregnancy for the treatment of gestational diabetes mellitus (GDM) remains controversial owing to concerns around safety and efficacy. This comprehensive review outlines the physiological metabolic functions of metformin and synthesizes existing literature and key knowledge gaps pertaining to the use of metformin in pregnancy across various end points in women with GDM. On the basis of current evidence, metformin reduces gestational weight gain, neonatal hypoglycaemia and macrosomia and increases insulin sensitivity. However, considerable heterogeneity between existing studies and the grouping of aggregate and often inharmonious data within meta-analyses has led to disparate findings regarding the efficacy of metformin in treating hyperglycaemia in GDM. Innovative analytical approaches with stratification by individual-level characteristics (for example, obesity, ethnicity, GDM severity and so on) and treatment regimens (diagnostic criteria, treatment timing and follow-up duration) are needed to establish efficacy across a range of end points and to identify which, if any, subgroups might benefit from metformin treatment during pregnancy.

D-Chiro Inositol Supplementation and the Occurrence of Gestational Diabetes: A Randomized Controlled Trial in China

To investigate the effect of D-chiro inositol (DCI) supplementation on perinatal outcomes in pregnant women at high risk of gestational diabetes mellitus (GDM), we conducted a prospective, randomized, placebo-controlled study. Eligibility criteria included women aged ≥ 35 years old, with a pre-pregnancy body mass index ≥ 24 kg/m2, having a family history of type 2 diabetes, having a history of GDM, polycystic ovary syndrome, or a history of delivering macrosomia infants. Participants who were recruited at a gestational age of 12-16 weeks, were randomly to receive either DCI 500 mg twice daily or to receive a placebo for 12 weeks. Outcome measured included the occurrence of GDM and other perinatal outcomes. Between 2020 and 2022, 276 participants were enrolled, with 139 in the DCI Group and 137 in the Control Group. Occurrence of GDM was significantly lower in the DCI group compared to that in placebo group (24.8% vs. 38.1%, p = 0.027). A significant difference was observed in the 1-h glycemia during the oral glucose tolerance test (OGTT) (8.35 ± 1.55 vs. 8.81 ± 1.85, p = 0.043), however, no significant differences in the fasting glucose level or 2-h glycemia between the two groups. The mean birth weight of newborns in the control group was significantly heavier than in the DCI group (3487.9 ± 437.7 g vs. 3341.6 ± 420.1 g, p = 0.011). Therefore, DCI supplementation in early pregnancy can reduce the occurrence of GDM in women at high risk. Trial Registration: ClinicalTrials.gov identifier: NCT 04801485.

15. Management of Diabetes in Pregnancy: Standards of Care in Diabetes-2025

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Efficacy and safety of metformin during pregnancy: an update

During the last decades, gestational diabetes mellitus (GDM) prevalence has been on the rise. While insulin remains the gold standard treatment for GDM, metformin use during pregnancy is controversial. This review aimed to comprehensively assess the available data on the efficacy and safety of metformin during pregnancy, both for the mother and the offspring. Metformin has been validated for maternal efficacy and safety, achieving comparable glycemic control with insulin. Additionally, it reduces maternal weight gain and possibly the occurrence of hypertensive disorders. During the early neonatal period, metformin administration does not increase the risk of congenital anomalies or other major adverse effects, including lower APGAR score at 5 min, neonatal intensive care unit admissions, and respiratory distress syndrome. Several studies have demonstrated a reduction in neonatal hypoglycemia. Metformin has been associated with an increase in preterm births and lower birth weight, although this effect is controversial and depends on the indication for which it was administered. Evidence indicates possible altered fetal programming and predisposition to childhood obesity and metabolic syndrome during adulthood after use of metformin in pregnancy. With critical questions still requiring a final verdict, ongoing research on the field must be conducted.

Prophylactic administration of metformin reduces gestational diabetes mellitus incidence in the high-risk populations: a meta-analysis : Metformin for gestational diabetes prevention

Metformin exerts a good efficacy for gestational diabetes mellitus (GDM) treatment by regulating gluconeogenesis and insulin resistance, while no consensus about its preventive effect on GDM is reached yet. Thus, this meta-analysis aimed to comprehensively investigate the prophylactic administration of metformin in pregnant women at high risk of GDM. Databases (EMBASE, PubMed, Cochrane, CNKI, Wanfang, CQVIP) were searched to screen papers concerning the GDM prevention using metformin in women at high risk of GDM (polycystic ovary syndrome (PCOS), obese, and pregestational insulin resistance patients) until January 2023. Our study showed that five cohort studies and fifteen randomized controlled trials (RCTs) involving 3911 women were included. Pooled analysis showed that prophylactic metformin treatment (vs. control treatment) greatly reduced GDM rate (relative risk (RR) = 0.59, 95% confidence intervals (CI): 0.43-0.80). Subgroup analyses also revealed that prophylactic metformin treatment (vs. control treatment) decreased the GDM rate in the following patients' types: (1) in Asians (RR = 0.31, 95% CI: 0.23-0.41), (2) in PCOS patients (RR = 0.42, 95% CI: 0.26-0.68), and (3) in patients receiving high dose of metformin (mean dose > 1000 mg) (RR = 0.59, 95% CI: 0.42-0.83). Concerning the quality of involved studies, the overall risk of bias was low. Egger's test implied that no publication bias existed in the findings. Moreover, sensitivity analysis suggested the pleasing robustness of the results. In conclusion, prophylactic metformin reduces GDM incidence in high-risk pregnant women, indicating its early-application benefits.

15. Management of Diabetes in Pregnancy: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Screening and management of major endocrinopathies during pregnancy: an update

Endocrinopathies during pregnancy constitute a challenging issue, being prevalent and requiring appropriate management to avoid maternal and fetal complications. This review aims to summarize and present major endocrine problems during pregnancy, the appropriate screening, maternal monitoring and management, fetal monitoring, and follow-up. Glucose metabolism, thyroid function, as well as calcium and vitamin D metabolism are the main endocrine domains that should be screened and monitored during pregnancy. Gestational diabetes mellitus (GDM) is the most prevalent endocrine disease during pregnancy, followed by thyroid disorders. Specific recommendations are provided for the optimal clinical care of pregnant women and their offspring for GDM, thyroid disorders, and calcium and vitamin D disorders.

15. Management of Diabetes in Pregnancy: Standards of Care in Diabetes-2023

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

15. Management of Diabetes in Pregnancy: Standards of Medical Care in Diabetes-2022

The American Diabetes Association (ADA) "Standards of Medical Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee (https://doi.org/10.2337/dc22-SPPC), are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations, please refer to the Standards of Care Introduction (https://doi.org/10.2337/dc22-SINT). Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Metformin for diabetes prevention: update of the evidence base

We have conducted a narrative review based on a structured search strategy, focusing on the effects of metformin on the progression of non-diabetic hyperglycemia to clinical type 2 diabetes mellitus. The principal trials that demonstrated a significantly lower incidence of diabetes in at-risk populations randomized to metformin (mostly with impaired glucose tolerance [IGT]) were published mainly from 1999 to 2012. Metformin reduced the 3-year risk of diabetes by -31% in the randomized phase of the Diabetes Prevention Program (DPP), vs. -58% for intensive lifestyle intervention (ILI). Metformin was most effective in younger, heavier subjects. Diminishing but still significant reductions in diabetes risk for subjects originally randomized to these groups were present in the trial's epidemiological follow-up, the DPP Outcomes Study (DPPOS) at 10 years (-18 and -34%, respectively), 15 years (-18 and -27%), and 22 years (-18 and -25%). Long-term weight loss was also seen in both groups, with better maintenance under metformin. Subgroup analyses from the DPP/DPPOS have shed important light on the actions of metformin, including a greater effect in women with prior gestational diabetes, and a reduction in coronary artery calcium in men that might suggest a cardioprotective effect. Improvements in long-term clinical outcomes with metformin in people with non-diabetic hyperglycemia ("prediabetes") have yet to be demonstrated, but cardiovascular and microvascular benefits were seen for those in the DPPOS who did not vs. did develop diabetes. Multiple health economic analyses suggest that either metformin or ILI is cost-effective in a community setting. Long-term diabetes prevention with metformin is feasible and is supported in influential guidelines for selected groups of subjects. Future research will demonstrate whether intervention with metformin in people with non-diabetic hyperglycemia will improve long-term clinical outcomes.

No impact of gestational diabetes mellitus on pregnancy complications in women with PCOS, regardless of GDM criteria used

Polycystic ovary syndrome (PCOS) is characterized by the presence of insulin resistance, and women with PCOS have high prevalence of gestational diabetes (GDM). Both conditions have been associated with increased risk for pregnancy complications such as preterm birth, preeclampsia and increased offspring birth weight. We aimed to estimate the prevalence of GDM in women with PCOS using both previous and new diagnostic criteria, and to analyse whether the risk of pregnancy complications increased with the presence of GDM. In addition, we aimed to assess the response to metformin treatment in PCOS women with GDM. We performed post-hoc analysis of three prospective, double blinded studies of altogether 791 pregnant women with PCOS randomized to either metformin or placebo treatment from first trimester to delivery. Glucose data allowing GDM classification after previous (WHO 1999) and new (WHO 2013 and Norwegian 2017) diagnostic criteria were available for 722 of the women. Complications such as preeclampsia, late miscarriage and preterm birth, birth weight and gestational age were correlated to the presence of GDM and metformin treatment. The prevalence of GDM was 28.3% (WHO 1999), 41.2% (WHO 2013) and 27.2% (Norwegian 2017). Having GDM already in first trimester associated with increased risk for late miscarriage (p<0.01). Having GDM according to newer criteria correlated to increased maternal age and BMI (p<0.001). Otherwise, having GDM (any criteria) correlated neither to the development of preeclampsia, nor to birth weight z-score or the proportion of offspring being large for gestational weight. Maternal age and BMI, parity and gestational weight gain, but not GDM or metformin treatment, were determinants for birth weight z-score. Conclusion: in pregnant women with PCOS, having GDM did not increase the risk for other pregnancy complications except for an increased risk for late miscarriage among those with GDM already in the first trimester.

Therapeutic Potentials of Low-Dose Tacrolimus for Aberrant Endometrial Features in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a major anovulatory infertility affecting a great proportion of women of childbearing age and is associated with obesity, insulin resistance and chronic inflammation. Poor endometrial receptivity and recurrent implantation failure are major hurdles to the establishment of pregnancy in women with PCOS. The accumulating body of evidence obtained from experimental and clinical studies suggests a link between inherent adaptive and innate immune irregularities and aberrant endometrial features in PCOS. The use of conventional therapeutic interventions such as lifestyle modification, metformin and ovarian stimulation has achieved limited clinical success in restoring ovulation and endometrial receptivity in women with PCOS. Unlike other immunosuppressive drugs prescribed in the clinical management of autoimmune and inflammatory disorders that may have deleterious effects on fertility and fetal development, preclinical studies in mice and in women without PCOS but with repeated implantation failure revealed potential therapeutic benefits for the use of low-dose tacrolimus in treating female infertility. Improved systemic and ovarian immune functions, endometrial progesterone receptor and coreceptor expressions and uterine vascular adaptation to pregnancy were among features of enhanced progesterone-receptor sensitivity in the low-dose tacrolimus-treated mouse model of the disease. In this review, we have compiled available experimental and clinical data in literature on endometrial progesterone resistance and current therapeutic options, as well as mechanisms of actions and reported outcomes relevant to the potential therapeutic benefits for the use of low-dose tacrolimus in treating PCOS-associated female infertility.

Metformin is comparable to insulin for pharmacotherapy in gestational diabetes mellitus: A network meta-analysis evaluating 6046 women

CONTEXT

The comparative efficacy of gestational diabetes (GDM) treatments lack conclusive evidence for choice of first-line treatment.

OBJECTIVES

The aim of this study was to compare the efficacy of metformin and glibenclamide to insulin using a core outcome set (COS) to unify outcomes across trials investigating the treatment of gestational diabetes mellitus.

STUDY DESIGN

A network meta-analysis (NMA) was conducted.

DATA-SOURCE

PubMed, Embase, and Cochrane Controlled Register of Trials were searched from inception to January 2020.

STUDY SELECTION

RCTs that enrolled pregnant women who were diagnosed with GDM and that compared the efficacy of different pharmacological interventions for the treatment of GDM were included.

META-ANALYSIS

A generalized pairwise modelling framework was employed.

RESULTS

A total of 38 RCTs with 6046 participants were included in the network meta-analysis. Compared to insulin, the estimated effect of metformin indicated improvements for weight gain (WMD -2·39 kg; 95% CI -3·31 to -1·46), maternal hypoglycemia (OR 0.34; 95% CI 0.12 to 0·97) and LGA (OR 0.61; 95% CI 0.38 to 0·98). There were also improvements in estimated effects for neonatal hypoglycemia (OR 0.48; 95% CI 0.19 to 1·25), pregnancy induced hypertension (OR 0.63; 95% CI 0.37 to 1·06), and preeclampsia (OR 0.74; 95% CI 0.538 to 1·04), though with limited evidence against our model hypothesis of equivalence with insulin for these outcomes.

CONCLUSION

Metformin is, at least, comparable to insulin for the treatment of GDM. Glibenclamide appears less favorable, in comparison to insulin, than metformin.

Management of Women with Polycystic Ovary Syndrome During Pregnancy

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among reproductive age women and is associated with subfertility and adverse perinatal outcomes, which may include early pregnancy loss, gestational diabetes mellitus, hypertensive spectrum disorder, preterm birth, fetal growth disorders, and cesarean deliveries. The phenotypic heterogeneity, different diagnostic criteria, and PCOS-related conditions that women enter pregnancy with have limited evidenced-based studies and guidelines to reduce pregnancy complications among this high-risk population. This review summarizes the available evidence on the approach and management of women with PCOS preconception, prenatal, and postpartum.

The Current and Potential Therapeutic Use of Metformin-The Good Old Drug

Metformin, one of the oldest oral antidiabetic agents and still recommended by almost all current guidelines as the first-line treatment for type 2 diabetes mellitus (T2DM), has become the medication with steadily increasing potential therapeutic indications. A broad spectrum of experimental and clinical studies showed that metformin has a pleiotropic activity and favorable effect in different pathological conditions, including prediabetes, type 1 diabetes mellitus (T1DM) and gestational diabetes mellitus (GDM). Moreover, there are numerous studies, meta-analyses and population studies indicating that metformin is safe and well tolerated and may be associated with cardioprotective and nephroprotective effect. Recently, it has also been reported in some studies, but not all, that metformin, besides improvement of glucose homeostasis, may possibly reduce the risk of cancer development, inhibit the incidence of neurodegenerative disease and prolong the lifespan. This paper presents some arguments supporting the initiation of metformin in patients with newly diagnosed T2DM, especially those without cardiovascular risk factors or without established cardiovascular disease or advanced kidney insufficiency at the time of new guidelines favoring new drugs with pleotropic effects complimentary to glucose control. Moreover, it focuses on the potential beneficial effects of metformin in patients with T2DM and coexisting chronic diseases.

Core outcomes in gestational diabetes for treatment trials: The Gestational Metabolic Group treatment set

Aims

With the rising number of outcomes being reported following gestational diabetes (GDM), the outcomes in existing studies vary widely making it challenging to compare and contrast the effectiveness of different interventions for GDM. The purpose of this study was to develop a core outcome and measurement set (COS) for GDM treatment trials.

Materials & Methods

A Delphi study with structured consultation with stakeholders and discussion within a specialist Gestational Metabolic Group (GEM) were combined with a comprehensive systematic search across different databases (PubMed, Cochrane Library, and Embase). Several Delphi rounds over 2 years were conducted culminating in this report.

Results

The process resulted in a targeted set of outcomes constituting a “GEM treatment set” aligned with expert opinion. The final COS also included a measurement set for the 11 important clinical outcomes from three major domains: maternal metabolic, fetal, and pregnancy related.

Conclusions

Based on the results of this study, it is recommended that future clinical trials on GDM report outcomes uniformly keeping to the recommended COS outcomes.

Methodological issues of systematic reviews and meta-analyses in the field of sleep medicine: A meta-epidemiological study

An increasing number of systematic reviews and meta-analyses (SRMAs) have been published in the field of sleep medicine. We evaluated the methodological issues of these SRMAs. A protocol was developed in advance. Three databases were searched from inception to October 2019 for SRMAs published in major academic journals of sleep medicine that assessed healthcare interventions. The AMSTAR 2.0 instrument was used to evaluate the methodological issues and a multivariable regression analysis was conducted to investigate potential measures associated with methodological validity. We identified 163 SRMAs. The median number of missing safeguards of these SRMAs was 7 out of 16 (Interquartile range, IQR: 6-9), and on average, two of these missing safeguards were critical weaknesses. Our regression analysis suggested that SRMAs published in recent years (β = 0.16; 95%CI: 0.08, 0.24; p = 0.002), with the first author from Europe (β = 0.08; 95%CI: 0.02, 0.14; p = 0.013) tend to have higher relative methodological ranks. In conclusion, the methodological validity for current SRMAs in sleep medicine was poor. Further efforts to improve the methodological validity are needed.

The MethodologicAl STandards for Epidemiological Research (MASTER) scale demonstrated a unified framework for bias assessment

OBJECTIVE

This paper presents a unified framework for assessment of the methodological quality of analytic study designs.

STUDY DESIGN AND SETTING

A systematic review of 393 methodological quality assessment tools that updated a previous assessment with 100 tools. Tool items were extracted, examined and reworded. Bias domains and finally methodological standards to be fulfilled were defined.

RESULTS

There were 36 unique methodological safeguards that were categorized into seven methodological standards to be fulfilled in the MASTER scale. These methodological standards reflect initial and ongoing equivalence in particular areas, including equal recruitment, equal retention, equal ascertainment, equal implementation, equal prognosis, sufficient analysis, and temporal precedence.

CONCLUSION

This approach unifies existing methods for methodological quality assessment and will be useful for (1) clinical researchers when a bias assessment of clinical research studies is required across analytical designs, (2) promoting a unified framework for bias assessment.

Endometrial function in women with polycystic ovary syndrome: a comprehensive review

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. An endometrial component has been suggested to contribute to subfertility and poor reproductive outcomes in affected women.

OBJECTIVE AND RATIONALE

The aim of this review was to determine whether there is sufficient evidence to support that endometrial function is altered in women with PCOS, whether clinical features of PCOS affect the endometrium, and whether there are evidence-based interventions to improve endometrial dysfunction in PCOS women.

SEARCH METHODS

An extensive literature search was performed from 1970 up to July 2020 using PubMed and Web of Science without language restriction. The search included all titles and abstracts assessing a relationship between PCOS and endometrial function, the role played by clinical and biochemical/hormonal factors related to PCOS and endometrial function, and the potential interventions aimed to improve endometrial function in women with PCOS. All published papers were included if considered relevant. Studies having a specific topic/hypothesis regarding endometrial cancer/hyperplasia in women with PCOS were excluded from the analysis.

OUTCOMES

Experimental and clinical data suggest that the endometrium differs in women with PCOS when compared to healthy controls. Clinical characteristics related to the syndrome, alone and/or in combination, may contribute to dysregulation of endometrial expression of sex hormone receptors and co-receptors, increase endometrial insulin-resistance with impaired glucose transport and utilization, and result in chronic low-grade inflammation, immune dysfunction, altered uterine vascularity, abnormal endometrial gene expression and cellular abnormalities in women with PCOS. Among several interventions to improve endometrial function in women with PCOS, to date, only lifestyle modification, metformin and bariatric surgery have the highest scientific evidence for clinical benefit.

WIDER IMPLICATIONS

Endometrial dysfunction and abnormal trophoblast invasion and placentation in PCOS women can predispose to miscarriage and pregnancy complications. Thus, patients and their health care providers should advise about these risks. Although currently no intervention can be universally recommended to reverse endometrial dysfunction in PCOS women, lifestyle modifications and metformin may improve underlying endometrial dysfunction and pregnancy outcomes in obese and/or insulin resistant patients. Bariatric surgery has shown its efficacy in severely obese PCOS patients, but a careful evaluation of the benefit/risk ratio is warranted. Large scale randomized controlled clinical trials should address these possibilities.

Physical activity in pregnancy prevents gestational diabetes: A meta-analysis

AIMS

The effectiveness of physical activity (PA) programs for prevention of gestational diabetes (GDM) lacks conclusive evidence. The aim of this study was to generate clear evidence regarding the effectiveness of physical activity programs in GDM prevention to guide clinical practice.

METHODS

PubMed/Medline, ISI Web of Science, Scopus, and EMBASE were searched to identify the randomized trials (RCTs) published until June 2019. Randomised controlled trials enrolling women at high risk before the 20th week of gestation comparing the effect of PA interventions with usual care for prevention of GDM were retrieved. Data obtained were synthesised using a bias-adjusted model of meta-analysis.

RESULTS

A total of 1467 adult women in 11 eligible trials were included. The risk of GDM was significantly lower with PA, but only when it was delivered in the healthcare facility (RR 0.53; 95% CI 0.38-0.74). The number needed to treat with PA in pregnancy (compared to usual care) to prevent one GDM event was 18 (95% CI 14 - 29). The overall effect of PA interventions regardless of location of the intervention was RR 0.69 (95% CI 0.51 - 0.94).

CONCLUSIONS

This study provides evidence that in-facility physical activity programs started before the 20th week of gestation can significantly decrease the incidence of GDM among women at high risk.

Mitochondrial dysfunction in the fetoplacental unit in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy that is associated with d-glucose intolerance and foeto-placental vascular dysfunction. GMD causes mitochondrial dysfunction in the placental endothelium and trophoblast. Additionally, GDM is associated with reduced placental oxidative phosphorylation due to diminished activity of the mitochondrial F₀F₁-ATP synthase (complex V). This phenomenon may result from a higher generation of reactive superoxide anion and nitric oxide. Placental mitochondrial biogenesis and mitophagy work in concert to maintain cell homeostasis and are vital mechanisms securing the efficient generation of ATP, whose demand is higher in pregnancy, ensuring foetal growth and development. Additional factors disturbing placental ATP synthase activity in GDM include pre-gestational maternal obesity or overweight, intracellular pH, miRNAs, fatty acid oxidation, and foetal (and 'placental') sex. GDM is also associated with maternal and foetal hyperinsulinaemia, altered circulating levels of adiponectin and leptin, and the accumulation of extracellular adenosine. Here, we reviewed the potential interplay between these molecules or metabolic conditions on the mechanisms of mitochondrial dysfunction in the foeto-placental unit in GDM pregnancies.

Association of Metformin With Pregnancy Outcomes in Women With Polycystic Ovarian Syndrome Undergoing In Vitro Fertilization: A Systematic Review and Meta-analysis

IMPORTANCE

Metformin is widely used among women with polycystic ovary syndrome (PCOS). However, its associations with outcomes of in vitro fertilization or intracytoplasmic sperm injection and embryo transfer (IVF/ICSI-ET) in women with PCOS remain controversial.

OBJECTIVE

To assess whether metformin is associated with improved outcomes of IVF/ICSI-ET in women with PCOS.

DATA SOURCES

PubMed, Embase, and Cochrane were searched from database inception to January 31, 2020.

STUDY SELECTION

Only randomized clinical trials (RCTs) were included. Eligible studies enrolled women with PCOS undergoing infertility treatment with IVF/ICSI-ET and reported at least 1 outcome of IVF/ICSI-ET.

DATA EXTRACTION AND SYNTHESIS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta analyses guidelines. Two authors independently extracted the data. Study quality was evaluated using the GRADE system. Treatment effect was quantified using odds ratios (ORs) with 95% CIs using random-effect models with the Mantel-Haenszel method.

MAIN OUTCOMES AND MEASURES

Ovarian hyperstimulation syndrome (OHSS), clinical pregnancy rate, and live birth rate.

RESULTS

A total of 12 RCTs, which collectively included 1123 women with PCOS undergoing infertility treatment with IVF/ICSI-ET, were identified. The risk of OHSS in women randomized to metformin was lower than in women not randomized to metformin (OR, 0.43; 95% CI, 0.24-0.78), although this difference was not significant for women with PCOS with a body mass index of less than 26 (OR, 0.67; 95% CI, 0.30-1.51). There was no significant difference in clinical pregnancy rate (OR, 1.24; 95% CI, 0.82-1.86) or live birth rate (OR, 1.23; 95% CI, 0.74-2.04) in the total population studied. However, in a post hoc analysis among women with a body mass index of 26 or greater, metformin treatment was associated with increased clinical pregnancy rates (OR, 1.71; 95% CI, 1.12-2.60).

CONCLUSIONS AND RELEVANCE

In this study, metformin treatment was associated with a decreased risk of OHSS but had no association with the overall clinical pregnancy rate or live birth rate among women with PCOS undergoing IVF/ICSI-ET. Metformin treatment should be carefully considered for women with PCOS undergoing IVF/ICSI-ET and may be more preferred for women with a body mass index greater than 26.