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.