Combined metformin-clomiphene in clomiphene-resistant polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials

Investigating the impact of trial retractions on the healthcare evidence ecosystem (VITALITY Study I): retrospective cohort study

OBJECTIVE

To investigate the impact of retracted trials on the production and use of healthcare evidence in the evidence ecosystem.

DESIGN

Retrospective cohort study based on forward citation searching.

DATA SOURCES

Retraction Watch up to 5 November 2024.

STUDY SELECTION

Randomised controlled trials in humans that were retracted for any reason.

METHODS

Forward citation searching via Google Scholar and Scopus was used to identify evidence synthesis research (21 November 2024) that quantitatively incorporated retracted trials. Data were independently extracted by two groups of researchers. The results of meta-analyses were updated after exclusion of the retracted trials. The proportions of meta-analyses that changed direction of the pooled effect and/or the significance of the P value were estimated. A generalised linear mixed model was used to investigate the association between the number of included studies and the impact, measured by odds ratio and 95% confidence interval (CI). The impact of distorted evidence on clinical practice guidelines was also investigated on the basis of citation searching.

RESULTS

The searches identified 1330 retracted trials and 847 systematic reviews that quantitatively synthesised retracted trials, with a total of 3902 meta-analyses that could be replicated. After the potential clustering effects were accounted for, the exclusion of the retracted trials led to a change in the direction of the pooled effect in 8.4% (95% CI 6.8% to 10.1%), in its statistical significance in 16.0% (14.2% to 17.9%), and in both direction and significance in 3.9% (2.5% to 5.2%) and a >50% change in the magnitude of the effect in 15.7% (13.5% to 17.9%). An obvious non-linear association existed between the number of included studies and the impact on the results, with a lower number of studies having higher impact (eg, for 10 studies versus ≥20 studies, change of direction: odds ratio 2.63, 95% CI 1.29 to 5.38; P<0.001). Evidence from 68 systematic reviews with conclusions distorted by retracted trials was used in 157 guideline documents.

CONCLUSION

Retracted trials have a substantial impact on the evidence ecosystem, including evidence synthesis, clinical practice guidelines, and evidence based clinical practice. Evidence generators, synthesisers, and users must pay attention to this problem, and feasible approaches that assist with easier identification and correction of such potential contamination are needed.

STUDY REGISTRATION

Open Science Framework (https://osf.io/7eazq/).

Mendelian randomization study showed no causality between metformin treatment and polycystic ovary syndrome

BACKGROUND

Despite previous clinical studies providing some evidence of an association between metformin treatment and polycystic ovary syndrome(PCOS), these findings remain controversial. To investigate whether the association reflect causality, a two-sample Mendelian randomization (MR) method was conducted.

METHODS

Data from genome-wide association studies were analyzed, with the exposure factor being metformin and the outcome variable being PCOS. The inverse variance weighted(IVW) was used as the primary method for MR analysis. In addition, MR-Egger, weighted median, heterogeneity tests, and sensitivity analyses were performed.

RESULTS

The initial and validation MR analyses indicated that genetically predicted metformin treatment had no effects on PCOS. Sensitivity analyses provided additional confirmation of the reliability of the MR results.

CONCLUSIONS

Our two-sample MR analysis did not find genetic evidence supporting a significant association between metformin treatment and PCOS.

Insulin-sensitizing agents for infertility treatment in woman with polycystic ovary syndrome: a narrative review of current clinical practice

PURPOSE

Polycystic ovary syndrome (PCOS) is an endocrine, metabolic, and reproductive disorder which, according to the Rotterdam criteria, affects up to 24% of women of childbearing age. Although the prevalence of infertility in this subpopulation of women is high, the optimal treatment has not been fully established yet. Insulin resistance is considered to be an important mechanism involved in the development of PCOS; hence, the aim of this narrative review is to present an overview of the current pharmacological insulin-sensitizing treatment modalities for infertile women with PCOS.

METHODS

A MEDLINE and PubMed search for the years 1990-2023 was performed using a combination of keywords. Clinical trials with insulin sensitizers used for infertility treatment as well as analyses of systematic reviews and meta-analyses were evaluated. When deemed necessary, additional articles referenced in the retrieved papers were included in this narrative review.

RESULTS

Several insulin-sensitizing compounds and various therapeutical protocols are available for infertility treatment of women with PCOS. Metformin is the most common adjuvant medication to induce ovulation in infertile women with PCOS and is more frequently administered in combination with clomiphene citrate than on its own. Recently, inositol and glucagon-like peptide-1 (GLP-1) receptor agonists have emerged as possible options for infertility treatment in PCOS.

CONCLUSION

The future of medical treatment of PCOS women with infertility lies in a personalized pharmacological approach, which involves various compounds with different mechanisms of action that could modify ovarian function and endometrial receptivity, ultimately leading to better overall reproductive outcomes in these women.

The use of metformin in women with polycystic ovary syndrome: an updated review

PURPOSES

Polycystic ovary syndrome (PCOS) is a major cause of female infertility, being present in up to 20% of women of childbearing age. Insulin resistance (IR) plays an important role in the pathophysiology of PCOS; therefore, its treatment may benefit women with the syndrome. The main drug used for IR management is metformin (MT). We aim to review the literature on the use of metformin in women with PCOS.

METHODS

Using the terms "metformin" and "polycystic ovary syndrome," we conducted a search the PubMed, EMBASE, and Google Scholar databases. The research was restricted to articles published in English. Initially, only published meta-analyses were included, in the absence of meta-analyzes, RCT and well-designed prospective studies were used.

RESULTS

Metformin increases success rates and decreases complication rates when used as an adjunctive medication for ovulation induction during low complexity assisted reproduction treatments and during ovarian stimulation for in vitro fertilization in women with PCOS. Evidence about the effect of metformin on fetal and obstetric complication rates is conflicting. Metformin is associated with high incidence of gastrointestinal symptoms; however, serious adverse effects are rare and there is no evidence of teratogenicity.

CONCLUSION

For women with PCOS, metformin is a good adjunctive medication for ovulation induction/stimulation for high and low complexity assisted reproduction therapies. The adverse effects are mostly mild, and there is no risk of teratogenicity, but the risk of long-term complications for the offspring is not yet defined. High heterogeneity of the studies limits extrapolation of findings, and further research is needed to determine which women will benefit most from the medication.

Molecular Mechanisms of Laparoscopic Ovarian Drilling and Its Therapeutic Effects in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common endocrinopathy, characterized by chronic anovulation, hyperandrogenism, and multiple small subcapsular cystic follicles in the ovary during ultrasonography, and affects 5-10% of women of reproductive age. PCOS is frequently associated with insulin resistance (IR) accompanied by compensatory hyperinsulinemia and, therefore, presents an increased risk of type 2 diabetes mellitus (DM). The pathophysiology of PCOS is unclear, and many hypotheses have been proposed. Among these hypotheses, IR and hyperandrogenism may be the two key factors. The first line of treatment in PCOS includes lifestyle changes and body weight reduction. Achieving a 5-15% body weight reduction may improve IR and PCOS-associated hormonal abnormalities. For women who desire pregnancy, clomiphene citrate (CC) is the front-line treatment for ovulation induction. Twenty five percent of women may fail to ovulate spontaneously after three cycles of CC treatment, which is called CC-resistant PCOS. For CC-resistant PCOS women, there are many strategies to improve ovulation rate, including medical treatment and surgical approaches. Among the various surgical approaches, one particular surgical method, called laparoscopic ovarian drilling (LOD), has been proposed as an alternative treatment. LOD results in an overall spontaneous ovulation rate of 30-90% and final pregnancy rates of 13-88%. These benefits are more significant for women with CC-resistant PCOS. Although the intra- and post-operative complications and sequelae are always important, we believe that a better understanding of the pathophysiological changes and/or molecular mechanisms after LOD may provide a rationale for this procedure. LOD, mediated mainly by thermal effects, produces a series of morphological and biochemical changes. These changes include the formation of artificial holes in the very thick cortical wall, loosening of the dense and hard cortical wall, destruction of ovarian follicles with a subsequently decreased amount of theca and/or granulosa cells, destruction of ovarian stromal tissue with the subsequent development of transient but purulent and acute inflammatory reactions to initiate the immune response, and the continuing leakage or drainage of "toxic" follicular fluid in these immature and growth-ceased pre-antral follicles. All these factors contribute to decreasing local and systemic androgen levels, the following apoptosis process with these pre-antral follicles to atresia; the re-starting of normal follicular recruitment, development, and maturation, and finally, the normalization of the "hypothalamus-pituitary-ovary" axis and subsequent spontaneous ovulation. The detailed local and systematic changes in PCOS women after LOD are comprehensively reviewed in the current article.

The cumulative success of ovulation induction therapy with gonadotrophins in therapy-naïve anovulatory women: An observational study

BACKGROUND

The use of gonadotrophins as a first-line treatment for anovulatory infertility has been limited by a perception of a risk of multi-fetal gestation and ovarian hyperstimulation syndrome (OHSS). However, it has recently been recognised as an acceptable first-line treatment if appropriate monitoring is performed.

AIMS

To determine the cumulative live birth rate, incidence of multiple gestation, cycle cancellation rate and incidence of OHSS for therapy-naïve anovulatory women undergoing ovulation induction with gonadotrophins.

MATERIALS AND METHODS

A prospective observational study of 258 patients undergoing ovulation induction with a 'low-dose step-up' protocol was performed over a three-year period across two fertility centres (40% of patients were currently or recently prescribed metformin).

RESULTS

Twenty-six percent of patients required concurrent use of luteinising hormone. The cumulative pregnancy and live birth rates were 22.5% and 18.2%, 40.3% and 34.5%, 47.7% and 41.1% after completion of the first, second and third cycles of stimulation, respectively, with a median duration of stimulation of 15 days. No patients developed OHSS and 10.5% of cycles were cancelled due to an excessive or no follicular response. The multiple pregnancy rate was 2%. The cumulative pregnancy rate was reduced for women over 35 years of age (23.8 vs 55.3%, P = 0.006) and for women with a body mass index greater than 25 kg/m² (40.6 vs 56.7%, P = 0.027)_. CONCLUSIONS: This study demonstrated that ovulation induction with gonadotrophin therapy, in the context of appropriate monitoring, is a safe and effective treatment for young therapy-naïve patients with anovulatory infertility.

Metformin Improves the Depression Symptoms of Women with Polycystic Ovary Syndrome in a Lifestyle Modification Program

BACKGROUND

Metformin is commonly prescribed to manage polycystic ovary syndrome (PCOS), which is one of the most common endocrine disorders among women of childbearing age and is associated with high prevalence rates of depression and anxiety.

OBJECTIVE

This study's objective was to determine the impact of prescribed metformin on depression and anxiety levels of patients with PCOS.

METHODS

This prospective, multi-center, cohort study examined the impact of prescribed metformin on the depression and anxiety of women with PCOS in four gynecology clinics in Saudi Arabia and Jordan. The women had recently been prescribed metformin along with lifestyle modifications, such as diet and exercise, and were compared to another group of women with PCOS who were prescribed lifestyle modifications only. Depression and anxiety were assessed at baseline and three months later using the Patient Health Questionnaire (PHQ-9) and the Generalized Anxiety Disorder (GAD-7) scale, respectively. Health-related quality of life was measured using the Short Form Health Survey (SF-36). Multiple logistic regression analyses were conducted to examine the impact of metformin on depression and anxiety.

RESULTS

Eighty-six women participated in the study: 53 were prescribed metformin with lifestyle modifications, and 33 were prescribed lifestyle modifications only. The women on metformin had 70% lower odds of having major depression (PHQ-9≥10) (OR=0.302, P=0.045); however, no significant effect of metformin on anxiety (GAD-7≥10) was found.

CONCLUSION

Metformin may have a role in the management of depression symptoms among patients with PCOS; however, its potential antidepressant effect should be further examined in randomized double-blind placebo-controlled clinical trials.

Medical and Surgical Treatment of Reproductive Outcomes in Polycystic Ovary Syndrome: An Overview of Systematic Reviews

Polycystic ovary syndrome (PCOS) is a common, complex condition that affects up to 18% of reproductiveaged women, causing reproductive, metabolic and psychological dysfunctions. We performed an overview and appraisal of methodological quality of systematic reviews that assessed medical and surgical treatments for reproductive outcomes in women with PCOS. Databases (MEDLINE, EMBASE, CINAHL PLUS and PROSPERO) were searched on the 15th of September 2017. We included any systematic review that assessed the effect of medical or surgical management of PCOS on reproductive, pregnancy and neonatal outcomes. Eligibility assessment, data extraction and quality assessment by the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) tool were performed in duplicate. We identified 53 reviews comprising 44 reviews included in this overview; the majority were moderate to high quality. In unselected women with PCOS, letrozole was associated with a higher live birth rate than clomiphene citrate (CC), while CC was better than metformin or placebo. In women with CC-resistant PCOS, gonadotrophins were associated with a higher live birth rate than CC plus metformin, which was better than laparoscopic ovarian drilling (LOD). LOD was associated with lower multiple pregnancy rates than other medical treatments. In women with PCOS undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), the addition of metformin to gonadotrophins resulted in less ovarian hyperstimulation syndrome (OHSS), and higher pregnancy and live birth rates than gonadotrophins alone. Gonadotrophin releasing hormone (GnRH) antagonist was associated with less OHSS, gonadotrophin units and shorter stimulation length than GnRH agonist. Letrozole appears to be a good first line treatment and gonadotrophins, as a second line treatment, for anovulatory women with PCOS. LOD results in lower multiple pregnancy rates. However, due to the heterogeneous nature of the included populations of women with PCOS, further larger scale trials are needed with more precise assessment of treatments according to heterogeneous variants of PCOS.

Fertility Treatment Options for Women With Polycystic Ovary Syndrome

Polycystic ovary syndrome is the most common endocrinological disorder in women of reproductive age. It is commonly associated with anovulatory subfertility, for which there are a range of treatment options available to help them conceive. These options are given in a step-wise manner with an appropriate selection of patients to maximise success rates with minimal complications. This review discusses the importance and involvement of multidisciplinary care when offering treatment to women with subfertility. Multidisciplinary care gives an excellent opportunity to identify, assess risk, and potentially prevent future morbidities and complications while treating women for fertility issues. We have also summarised the various options available for fertility treatment: pharmacological treatments, nonpharmacological intervention, and assisted reproductive technology.

A Review of Second- and Third-line Infertility Treatments and Supporting Evidence in Women with Polycystic Ovary Syndrome

In clomiphene-citrate-resistant anovulatory women with polycystic ovary syndrome (PCOS) and no other infertility factors, either metformin combined with clomiphene citrate or gonadotrophins could be used as a second-line pharmacological therapy, although gonadotrophins are more effective. Gonadotrophins could also be used as a second-line pharmacological therapy in anovulatory women with PCOS and clomiphene-citrate-failure. Laparoscopic ovarian surgery can also be used as a second-line therapy for ovulation induction in anovulatory women with clomiphene-citrate-resistant PCOS and no other infertility factors. The usefulness of letrozole as a second-line pharmacological treatment for ovulation induction in clomiphene-citrate-resistant women with PCOS requires further research. In terms of improving fertility, both pharmacological anti-obesity agents and bariatric surgery should be considered an experimental therapy in anovulatory women with PCOS and no other infertility factors. Where first- or second-line ovulation induction therapies have failed, in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI) could be offered as a third-line therapy in women with PCOS in the absence of an absolute indication for IVF/ICSI. For women with PCOS undergoing IVF/ICSI treatment, the gonadotropin-releasing hormone (GnRH) antagonist protocol is preferred and an elective frozen embryo transfer strategy could be considered. In assisted conception units with sufficient expertise, in-vitro maturation (IVM) of oocytes could be offered to women with PCOS.

Evidence summaries and recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome: assessment and treatment of infertility

STUDY QUESTION

What is the recommended assessment and management of infertile women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertize and consumer preference?

SUMMARY ANSWER

International evidence-based guidelines, including 44 recommendations and practice points, addressed prioritized questions to promote consistent, evidence-based care and improve the experience and health outcomes of infertile women with PCOS.

WHAT IS KNOWN ALREADY

Previous guidelines on PCOS lacked rigorous evidence-based processes, failed to engage consumer and multidisciplinary perspectives or were outdated. The assessment and management of infertile women with PCOS are inconsistent. The needs of women with PCOS are not being adequately met and evidence practice gaps persist.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Governance included a six continent international advisory and a project board, a multidisciplinary international guideline development group (GDG), consumer and translation committees. Extensive health professional and consumer engagement informed the guideline scope and priorities. The engaged international society-nominated panel included endocrinology, gynaecology, reproductive endocrinology, obstetrics, public health and other experts, alongside consumers, project management, evidence synthesis and translation experts. Thirty-seven societies and organizations covering 71 countries engaged in the process. Extensive online communication and two face-to-face meetings over 15 months addressed 19 prioritized clinical questions involving nine evidence-based reviews and 10 narrative reviews. Evidence-based recommendations (EBRs) were formulated prior to consensus voting within the guideline panel.

STUDY DESIGN, SIZE, DURATION

International evidence-based guideline development engaged professional societies and consumer organizations with multidisciplinary experts and women with PCOS directly involved at all stages. A (AGREE) II-compliant processes were followed, with extensive evidence synthesis. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was applied across evidence quality, desirable and undesirable consequences, feasibility, acceptability, cost, implementation and ultimately recommendation strength. The guideline was peer-reviewed by special interest groups across our partner and collaborating societies and consumer organizations, was independently assessed against AGREE II criteria and underwent methodological review. This guideline was approved by all members of the GDG and has been approved by the NHMRC.

MAIN RESULTS AND THE ROLE OF CHANCE

The quality of evidence (QOE) for the EBRs in the assessment and management of infertility in PCOS included very low (n = 1), low (n = 9) and moderate (n = 4) quality with no EBRs based on high-quality evidence. The guideline provides 14 EBRs, 10 clinical consensus recommendations (CCRs) and 20 clinical practice points on the assessment and management of infertility in PCOS. Key changes in this guideline include emphasizing evidence-based fertility therapy, including cheaper and safer fertility management.

LIMITATIONS, REASONS FOR CAUTION

Overall evidence is generally of low to moderate quality, requiring significantly greater research in this neglected, yet common condition. Regional health systems vary and a process for adaptation of this guideline is provided.

WIDER IMPLICATIONS OF THE FINDINGS

The international guideline for the assessment and management of infertility in PCOS provides clinicians with clear advice on best practice based on the best available evidence, expert multidisciplinary input and consumer preferences. Research recommendations have been generated and a comprehensive multifaceted dissemination and translation program supports the guideline with an integrated evaluation program.

STUDY FUNDING/COMPETING INTEREST(S)

The guideline was primarily funded by the Australian National Health and Medical Research Council of Australia (NHMRC) supported by a partnership with ESHRE and the American Society for Reproductive Medicine (ASRM). GDG members did not receive payment. Travel expenses were covered by the sponsoring organizations. Disclosures of conflicts of interest were declared at the outset and updated throughout the guideline process, aligned with NHMRC guideline processes. Dr Costello has declared shares in Virtus Health and past sponsorship from Merck Serono for conference presentations. Prof. Norman has declared a minor shareholder interest in the IVF unit Fertility SA, travel support from Merck and grants from Ferring. Prof. Norman also has scientific advisory board duties for Ferring. The remaining authors have no conflicts of interest to declare.

This article was not externally peer-reviewed by Human Reproduction Open.

Unilateral or bilateral laparoscopic ovarian drilling in polycystic ovary syndrome: a meta-analysis of randomized trials

PURPOSE

This systematic review and meta-analysis aimed to compare the effectiveness of unilateral vs. bilateral laparoscopic ovarian drilling (ULOD vs. BLOD) for improving fertility outcomes in infertile women with clomiphene-resistant polycystic ovary syndrome (PCOS) as well as its effect on ovarian reserve.

METHODS

Searches were conducted on PubMed, ScienceDirect, ClinicalTrials.gov, and CENTRAL databases from January 1984 to January 2017. Only randomized trials comparing ULOD with BLOD were included. The PRISMA Statement was followed. Main outcomes were ovulation and clinical pregnancy rates per woman randomized. Secondary outcomes were; live birth and miscarriage rates as well as postoperative serum anti-mullerian hormone (AMH) concentration and antral follicle count (AFC). Quality assessment was performed by the Cochrane Collaboration risk of bias tool.

RESULTS

Eight eligible trials (484 women) were analyzed. No significant difference was found in rates of ovulation (OR 0.73; 95% CI 0.47-1.11), clinical pregnancy (OR 0.56; 95% CI 0.22-1.41), live birth (OR 0.77; 95% CI 0.28-2.10), or miscarriage (OR 0.90; 95% CI 0.33-2.84) when ULOD was compared with BLOD. The reduction in AMH was comparable between the two procedures (MD 0.64 ng/ml; 95% CI - 0.08 to 1.36). A significantly higher AFC at 6-month follow-up was found with dose-adjusted ULOD (MD 2.20; 95% CI 1.01-3.39).

CONCLUSIONS

After carefully weighing up the well-known benefits of BLOD against a potential risk to ovarian reserve, clinicians could be advised to offer the fixed-dose ULOD to their infertile patients with clomiphene-resistant PCOS. This is concordant with the "primum non nocere" principal if LOD will be envisaged.

Obstetric and perinatal outcomes in subfertile patients who conceived following low technology interventions for fertility enhancement: a comprehensive review

PURPOSE

Low technology interventions for fertility enhancement (LTIFE) are strategies that avoid retrieval, handling, and manipulation of female gametes. The definition of LTIFE is yet to be widely accepted and clarified, but they are commonly used in milder cases of infertility and subfertility. Based on these considerations, the aim of the present study was comprehensively to review and investigate the obstetric and perinatal outcomes in subfertile patients who underwent LTIFE.

METHODS

A literature search up to May 2017 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science, and Google Scholar. An evidence-based hierarchy was used according to The Oxford Centre for Evidence-Based Medicine to determine which articles to include and analyze, and to provide a level of evidence of each association between intervention and outcome.

RESULTS

This analysis identified preliminary and low-grade evidence on the influence of LTIFE on obstetric and perinatal outcomes in subfertile women.

CONCLUSIONS

LTIFE women should deserve major consideration from Clinicians/Researchers of Reproductive Medicine, because these treatments could be potentially responsible for mothers' and babies' complications. So far, the lack of well-designed and unbiased studies makes further conclusions difficult to be drawn.

Comparative effectiveness of 9 ovulation-induction therapies in patients with clomiphene citrate-resistant polycystic ovary syndrome: a network meta-analysis

The comparative efficacies of ovulation-induction treatments in patients with clomiphene citrate-resistant (CCR) polycystic ovary syndrome (PCOS) are not well known. Therefore, we conducted a network meta-analysis to rank the reproductive efficacies of these treatments. We ultimately included 26 randomized clinical trials with 2722 participants and 9 types of therapies: clomiphene citrate (CC), metformin, letrozole, follicle stimulating hormone (FSH), human menopausal gonadotropin (hMG), unilateral laparoscopic ovarian drilling (ULOD), bilateral laparoscopic ovarian drilling (BLOD), the combination of metformin with letrozole (metformin+letrozole), and the combination of metformin with CC (metformin+CC). The network meta-analysis demonstrates that hMG therapy result in higher pregnancy rates than BLOD, ULOD and CC therapies. Pregnancy, live birth and ovulation rates are significantly higher in metformin+letrozole and FSH groups than CC group. The abortion rate in the metformin+letrozole group is significantly lower than that in the metformin+CC group. Ranking probabilities show that, apart from gonadotropin (FSH and hMG), metformin+letrozole is also potentially more effective in improving reproductive outcomes than other therapies. In conclusion, owing to the low quality of evidence and the wide confidence intervals, no recommendation could be made for the treatment of ovulation-induction in patients with CCR PCOS.

Mono-ovulation in women with polycystic ovary syndrome: a clinical review on ovulation induction

Polycystic ovary syndrome (PCOS) affects 5-10% of women of reproductive age and is the most common cause of anovulatory infertility. The treatment approaches to ovulation induction vary in efficacy, treatment duration and patient friendliness. The aim was to determine the most efficient, evidence-based method to achieve mono-ovulation in women diagnosed with PCOS. Publications in English providing information on treatment, efficacy and complication rates were included until September 2015. Systematic reviews, meta-analyses and randomized controlled trials were favoured over cohort and retrospective studies. Clomiphene citrate is recommended as primary treatment for PCOS-related infertility. It induces ovulation in three out of four patients, the risk of multiple pregnancies is modest and the treatment is simple and inexpensive. Gonadotrophins are highly efficient in a low-dose step-up regimen. Ovulation rates are improved by lifestyle interventions in overweight women. Metformin may improve the menstrual cycle within 1-3 months, but does not improve the live birth rate. Letrozole is effective for ovulation induction, but is an off-label drug in many countries. Ovulation induction in women with PCOS should be individualized with regard to weight, treatment efficacy and patient preferences with the aim of achieving mono-ovulation and subsequently the birth of a singleton baby.

Twenty years of ovulation induction with metformin for PCOS; what is the best available evidence?

The potential reproductive benefits of metformin, a drug endowed with the capacity to ameliorate insulin resistance in polycystic ovary syndrome (PCOS), has garnered much interest over the past 2 decades. In this review, randomized-controlled trials (RCT) and meta-analyses of RCT comparing metformin are critically appraised and summarized. PubMed and CENTRAL databases were consulted. Evidence is insufficient to favour the use of metformin or metformin plus clomiphene citrate instead of clomiphene citrate for ovulation induction in women with newly diagnosed PCOS. Evidence is also insufficient to recommend metformin as a primary treatment for non-obese women with PCOS. Metformin plus clomiphene citrate should be considered as an effective option in clomiphene citrate-resistant PCOS. In women with PCOS undergoing gonadotrophin ovulation induction, metformin significantly increased pregnancy and live birth rates (P < 0.0001 and P = 0.020, respectively) with reduced risk of cancelled cycles. A beneficial effect of metformin co-treatment in increasing clinical pregnancy rates and reducing the risk of OHSS in PCOS patients undergoing assisted reproduction techniques has been shown. No evidence was found of reduced risk of spontaneous abortion or increased risk of major anomalies in women with PCOS taking metformin during the first trimester.