The use of metformin in women with polycystic ovary syndrome: an updated review

Purposes Polycystic ovary syndrome (PCOS) is a major cause of female infertility, being present in up to 20% of women of childbearing age. Insulin resistance (IR) plays an important role in the pathophysiology of PCOS; therefore, its treatment may benefit women with the syndrome. The main drug used for IR management is metformin (MT). We aim to review the literature on the use of metformin in women with PCOS. Methods Using the terms "metformin" and "polycystic ovary syndrome," we conducted a search the PubMed, EMBASE, and Google Scholar databases. The research was restricted to articles published in English. Initially, only published meta-analyses were included, in the absence of meta-analyzes, RCT and well-designed prospective studies were used. Results Metformin increases success rates and decreases complication rates when used as an adjunctive medication for ovulation induction during low complexity assisted reproduction treatments and during ovarian stimulation for in vitro fertilization in women with PCOS. Evidence about the effect of metformin on fetal and obstetric complication rates is conflicting. Metformin is associated with high incidence of gastrointestinal symptoms; however, serious adverse effects are rare and there is no evidence of teratogenicity. Conclusion For women with PCOS, metformin is a good adjunctive medication for ovulation induction/stimulation for high and low complexity assisted reproduction therapies. The adverse effects are mostly mild, and there is no risk of teratogenicity, but the risk of long-term complications for the offspring is not yet defined. High heterogeneity of the studies limits extrapolation of findings, and further research is needed to determine which women will benefit most from the medication.