BACKGROUND: A systematic review of randomized controlled trials (RCTs) comparing whether metformin co-administration with gonadotrophins for ovulation induction (OI) with timed intercourse or IVF improves outcome in women with polycystic ovary syndrome (PCOS). METHODS: The quality of reporting of meta-analyses (QUOROM) guidelines were followed. A systematic computerized literature search of three bibliographic databases was performed. RESULTS: Eight RCTs were included in the overall review. Meta-analysis demonstrated that the co-administration of metformin to gonadotrophin OI does not significantly improve ovulation [odds ratio (OR) = 3.27; 95% confidence interval (95% CI) = 0.31–34.72] or pregnancy (OR = 3.46; 95% CI = 0.98–12.2) rates. Metformin co-administration to IVF treatment does not improve pregnancy (OR = 1.29; 95% CI = 0.84–1.98) or live birth (OR = 2.02, 95% CI = 0.98–4.14) rates but reduces the risk of ovarian hyperstimulation syndrome (OHSS) (OR = 0.21; 95% CI = 0.11–0.41, P < 0.00001). CONCLUSIONS: Current data on the use of metformin in the gonadotrophin OI or IVF treatment settings are inconclusive because of the review’s failure to exclude an important clinical treatment effect. Further RCTs are necessary to definitively clarify whether metformin co-administration during gonadotrophin OI or IVF will improve the efficacy of these treatments in PCOS women.

The object of this review was to compare metformin versus oral contraceptive pill (OCP) treatment in polycystic ovary syndrome. A systematic review and meta-analysis employing the principles of the Cochrane Menstrual Disorders and Subfertility Group was undertaken. Four randomized controlled trials (RCTs) (104 subjects) were included. Limited data demonstrated no evidence of a difference in effect between metformin and the OCP on hirsutism, acne or development of type 2 diabetes mellitus. There were no trials assessing diagnosis of cardiovascular disease or endometrial cancer. Metformin, in comparison with the OCP, was less effective in improving menstrual pattern [Peto odds ratio (OR) 0.08, 95% confidence interval (CI) 0.01–0.45) and in reducing the serum total testosterone level weighted mean difference (WMD) 0.54, 95% CI 0.22–0.86] but more effective in reducing fasting insulin (WMD −3.46, 95% CI − 5.39 to −1.52) and not increasing fasting triglyceride (WMD −0.48, 95% CI − 0.86 to −0.09) levels. Limited data demonstrated no evidence of a difference in effect between the two therapies on reducing fasting glucose or total cholesterol levels and severe adverse events. The limited RCT evidence to date does not show adverse metabolic risk with the use of the OCP compared with metformin. Further long-term RCTs are required.