Role of metformin for ovulation induction in infertile patients with polycystic ovary syndrome (PCOS): a guideline.

Metformin alone compared with placebo increases the ovulation rate in women with polycystic ovary syndrome (PCOS) but should not be used as first-line therapy for anovulation because oral ovulation induction agents such as clomiphene citrate or letrozole alone are much more effective in increasing ovulation, pregnancy, and live-birth rates in women with PCOS. There is fair evidence that metformin alone does not increase rates of miscarriage when stopped at the initiation of pregnancy and insufficient evidence that metformin in combination with other agents used to induce ovulation increases live-birth rates.