Comparison of the effects of letrozole and clomiphene citrate on ovulation induction in PCOS

Objective To compare the effects of letrozole and clomiphene citrate (CC) on ovulation induction in polycystis ovarian syndrome (PCOS) patients. Methods Seventy - eight female patients with PCOS caused abnormal ovulation were divided into two groups randomly. One group were treated with letrozole (5 mg, qd × 5 d) and the other group were treated with clomiphene (100 mg, qd × 5 d). Ultrasound scan was performed to monitor follicle development. When the diameter of the biggest follicle reached 20 ram, 5 000 IU HCG was injected to trigger ovulation. The ovulation rates, pregnancy rates, abortion rates and the thickness of endometrium were compared between the two groups. Results In letrozole group the ovulation rate and pregnancy rate per cycle were similar to those of CC group (P > 0.05), but the abortion rate significantly decreased (P < 0. 05). The thickness of endometrium on the day of HCG administration in the letrozole group was much thicker than that in CC group (P < 0.01). Conclusion Letrozole can attain good ovulation and pregnancy rates in PCOS women and reduce early abortion rates significantly. Key words: Letrozole;  Clomiphene;  Ovulation induction;  Polycystis ovarian syndrome