Efficacy of Letrozole in Ovulation Induction Compared to That of Clomiphene Citrate in Patients with Polycystic Ovarian Syndrome

Objective: To compare the efficacy of letrozole with clomiphene citrate for ovulation induction in patients with polycystic ovarian syndrome (PCOS).

Study Design: In this clinical trial, 107 infertile patients with PCOS received either 100 mg clomiphene citrate (n = 57) or 5 mg letrozole (n = 50) daily since day 3-7 of their menstrual cycle. Human chorionic gonadotropin (hCG) was administered at a dose of 10,000 IU when at least 1 mature follicle was detected. A single intrauterine insemination was performed 34 hours later. Then the size, number and growth rate of follicles, ovulation rate, endometrial thickness and pregnancy rate were measured in both groups.

Results: The number and the size of mature follicles were similar between the 2 groups. The pregnancy rate in letrozole group was higher than that in the clomiphene group (20% vs. 14%), but the difference was not significant (p = 0.286). In letrozole group, 86% of patients developed mature follicles, all showing ovulation, whereas 72% of patients in clomiphene citrate group developed mature follicles (p = 0.07).

Conclusion: Letrozole might be an acceptable alternative to clomiphene citrate to induce ovulation and pregnancy in PCOS patients.