Randomized controlled trial of different doses of metformin for ovulation induction in infertile women with polycystic ovary syndrome

Aim: To compare the efficacy of 1000 mg and 1700 mg of metformin on ovulation induction in polycystic ovary syndrome (PCOS) women. Material and Methods: A randomized controlled trial was conducted at Ramathibodi Hospital, Mahidol University, Bangkok, Thailand of 60 PCOS women diagnosed by Rotterdam criteria. Group A (30 women) and B (30 women) received 1000 mg and 1700 mg/day of metformin, respectively. Clomiphen citrate 50-150 mg per day for 5 days was added, if no dominant follicle developed. The main outcome measures were ovulation and pregnancy rates, fasting insulin (FI), testosterone (T), androstenedione (ADD) and DHEAS before and 4 weeks after metformin. Results: The ovulation rate did not differ between the groups (84.8% vs 87.7% between groups A and B, P = NS). Most of the women developed one follicle (91% in group A and 88.2% in group B, P = NS). The pregnancy rate in group A (46.4% per woman and 12.4% per ovulatory cycle) did not differ from that in group B (51.9% per woman and 13.2% per ovulatory cycle, P = NS). With regard to dosages, the ovulation rate in PCOS women without insulin resistance (IR) was significantly higher than those with IR. FI, T and ADD were significantly decreased after 4 weeks of metformin in both groups. Conclusion: 1000 mg of metformin had as high efficacy as 1700 mg on induction of ovulation and pregnancy in PCOS women.