A systematic review and meta-analysis of metformin among patients with polycystic ovary syndrome undergoing assisted reproductive technology procedures

Background Metformin is used among patients with polycystic ovary syndrome (PCOS), but findings for its effects on outcomes of assisted reproductive technology (ART) have been conflicting. Objectives To compare ART outcomes among women with PCOS who were and were not given metformin. Search strategy Databases were searched for reports published in English between 2002 and 2013, using combinations of the terms "polycystic ovary syndrome," "PCOS," "insulin-sensitizing," and "metformin." Selection criteria Randomized controlled trials of metformin versus placebo among women with PCOS undergoing ART were included if they assessed rates of pregnancy, live birth, spontaneous abortion, multiple pregnancy, and/or ovarian hyperstimulation syndrome (OHSS). Data collection and analysis Data were extracted from included studies. The Mantel-Haenzel random-effects model was used for meta-analyses. Main results Twelve studies (1516 participants) were included. No significant differences were recorded between metformin and placebo groups for rates of pregnancy (risk ratio [RR] 1.11, 95% CI 0.92-1.33), live birth (RR 1.12, 0.92-1.36), spontaneous abortion (RR 1.00, 0.60-1.67), or multiple pregnancy (RR 0.96, 0.47-1.96). However, OHSS rate was significantly lower among patients who received metformin than among those who received placebo (RR 0.44, 0.26-0.77). Conclusions Metformin does not improve ART outcomes among patients with PCOS, but does significantly reduce their risk of OHSS.