Impact of metformin therapy on ovarian stimulation and outcome in 'coasted' patients with polycystic ovary syndrome undergoing in-vitro fertilization

This study was designed to determine if metformin therapy improves ovarian stimulation and IVF outcomes in coasted patients with clomiphene-resistant polycystic ovarian syndrome (PCOS). A retrospective data analysis was performed on women with clomiphene citrate-resistant PCOS treated with or without metformin, who underwent 72 cycles of IVF-embryo transfer with intracytoplasmic sperm injection (ICSI). In 59 cycles, patients were coasted to allow oestradiol concentrations to drop before human chorionic gonadotrophin administration. In patients undergoing coasting, the outcome of IVF with ICSI was compared in those who were treated and untreated. In patients treated with metformin, follicular fluid concentrations of testosterone and insulin were significantly lower (60.5 +/- 5 versus 79.1 +/- 6 ng/dl; P < 0.05 and 18 +/- 2.5 versus 22 +/- 2.4 micro IU/ml; P < 0.05 respectively), and the mean number of oocytes retrieved (22.3 +/- 2.4 versus 19.7 +/- 1.6) did not differ. The metformin-treated group showed an increase in the mean number of mature oocytes, oocytes fertilized and cleaving embryos (4-cell or greater by 72 h). However, in the group of patients undergoing coasting, maximum oestradiol concentrations and number of days of coasting were all lower in the metformin-treated group with increased clinical pregnancy rates (71 versus 30%, P < 0.05). Therefore, metformin use appears beneficial in improving IVF outcomes in clomiphene citrate-resistant PCOS patients.