Effects of metformin on early pregnancy loss in the polycystic ovary syndrome

Polycystic ovary syndrome is the most common form of female infertility in the United States. In addition to poor conception rates, pregnancy loss rates are high (30-50%) during the first trimester. We hypothesized that hyperinsulinemic insulin resistance contributes to early pregnancy loss in the syndrome, and that decreasing hyperinsulinemic insulin resistance with metformin during pregnancy would reduce the rate of early pregnancy loss. We conducted a retrospective study of all women with polycystic ovary syndrome who were seen in an academic endocrinology clinic within the past 4.5 yr and who became pregnant during that time. Sixty-five women received metformin during pregnancy (metformin group) and 31 women did not (control group). The early pregnancy loss rate in the metformin group was 8.8% (6 of 68 pregnancies), as compared with 41.9% (13 of 31 pregnancies) in the control group (P < 0.001). In the subset of women in each group with a prior history of miscarriage, the early pregnancy loss rate was 11.1% (4 of 36 pregnancies) in the metformin group, as compared with 58.3% (7 of 12 pregnancies) in the control group (P = 0.002). Metformin administration during pregnancy reduces first-trimester pregnancy loss in women with the polycystic ovary syndrome.