Comparison of metformin and clomiphene citrate therapy for induction of ovulation in the polycystic ovary syndrome

Objective To compare the efficacy of metformin and clomiphene citrate (CC) therapies for ovulation induction in anovulatory infertile women with polycystic ovary syndrome (PCOS). Methods A total of 69 consecutive infertile, anovulatory women with PCOS were enrolled in this prospective, non-randomized trial. The women were prescribed either 1,700 mg/day metformin or CC with a starting dose of 50 mg/day up to 150 mg/day for a period of six consecutive cycles. Results Metformin and CC groups were followed for a total of 136 and 94 cycles, respectively. Metformin group had lower rates of ovulation when compared with CC group (32.3 vs. 60.6%, respectively; p = 0.004). There was no statistical difference in pregnancy rates per cycle between the treatment groups (8 vs. 11.7%, respectively; p = 0.33) leading to similar cumulative pregnancy rates (36.6 vs. 35.4%, respectively; p = 0.45). No difference was observed among the abortion rates (10 vs. 10%, respectively; p > 0.05) between the groups. Discussion Although metformin and CC are two effective first-line approaches for improving pregnancy rates in anovulatory PCOS women, CC is associated with higher rates of ovulation.