Metformin is effective as first-line therapy in PCOS-induced anovulation, according to a recently published review and meta-analysis. The drug may also have the added benefit of improving the metabolic syndrome.
Researchers from Australia reviewed 13 trials that included a population of 543 women with polycystic ovary syndrome. They calculated that metformin is almost four times as effective at inducing ovulation as placebo, and that the combination of metformin and clomiphene is about 4.41 times as effective as clomiphene alone. In addition, metformin reduces fasting insulin concentrations, blood pressure, and low-density lipoprotein cholesterol. However, the drug may cause nausea, vomiting, and other gastrointestinal disturbances, and data regarding long-term safety and use in pregnancy are lacking.
Lord JM, Flight IH, Norman RJ. Metformin in polycystic ovary syndrome: systematic review and meta-analysis. BMJ. 2003;327:951-953.