The role of metformin in ovulation induction: Current status

To define the exact role of metformin in ovulation induction, it is crucial to distinguish three different indications: naïve PCOS, CC-resistant PCOS and ART. In naïve PCOS: metformin as compared to placebo has been shown to improve ovulation rates, but metformin did not exert significant advantage over CC with respect to cumulative ovulation, pregnancy or live-birth rates. The combined approach of metformin plus CC is not better than CC or metformin monotherapy in naïve PCOS. In CC-resistant patients: metformin has no benefit over placebo in ovulation, pregnancy, and live-birth rates as a single agent, but the combination of metformin and CC significantly improved ovulation and pregnancy rates when compared with CC alone. However, combined therapy did not improve the odds of live birth. Metformin pretreatment improves the efficacy of CC in PCOS patients with CC resistance. In PCOS patients scheduled for ART: metformin addition to gonadotropins reduces the duration of gonadotropins administration and the doses of gonadotropins required, and increases the rate of monoovulations, reducing the risk of cancelled cycles. Metformin co-administration to IVF treatment does not improve pregnancy or live-birth rates but reduces the risk of OHSS.