Efficacy of metformin supplementation during ovarian stimulation of lean PCOS patients undergoing in vitro fertilization

Objective. To evaluate the effect of metformin addition during ovarian hyperstimulation on cycle parameters and outcome of in vitro fertilization (IVF) treatment in polycystic ovary syndrome (PCOS) patients with a body mass index (BMI) 28 kg/m2. Design. Retrospective review of patients' records. Setting. Istanbul Memorial Hospital Assisted Reproductive Treatment Unit. Population. A total of 339 non-obese PCOS patients undergoing IVF were evaluated according to the supplementation of metformin. Methods. Cycle parameters and IVF outcomes of 220 patients given metformin were compared to those of 119 patients treated without metformin. Main outcome measures. Implantation and pregnancy rates. Results. Metformin co-treatment led to significantly lower peak E2 levels (3,481 pg/ml vs. 4,192 pg/ml; p 0.0001). However, gonadotropin consumption, stimulation duration, numbers of total and mature oocytes retrieved, fertilization rate, and ratio of grade I embryos developed were similar in both groups. In the metformin administered group, significantly higher implantation (25% vs. 18%; p=0.003) and pregnancy rates (58% vs. 45%; p=0.04) were achieved. Abortion and moderate-severe ovarian hyperstimulation syndrome rates were found to be similar in both groups. Conclusions. Although metformin use was especially and strongly recommended in obese PCOS cases, its supplementation during IVF in PCOS patients with a BMI 28 kg/m2 was observed to be beneficial and efficacious.