A prospective, randomized trial comparing the effects of letrozole versus clomiphene citrate for induction of ovulation and pregnancy rate in women with polycystic ovary syndrome

Objective: To compare the effects of letrozole and clomiphene citrate (CC) for ovulation induction in women with polycystic ovary syndrome (PCOS).Design: Prospective, randomized, not blinded, controlled trial.Materials and Methods: This prospective, randomized clinical trial included 127 patients of infertile women with PCOS. The first group comprised 66 patients who received letrozole (2.5–5 mg) daily and the second group 61 patients who received (50–100 mg) CC daily for 5 days starting on day 3 of menses. Both the groups were followed by ultrasound until the dominant follicle reached a diameter ≥18 mm, human chorionic gonadotropin (hCG) 10,000 IU was given, and timed intercourse was advised. The treatment continued for three cycles in both the groups.Main Outcome Measures: Occurrence of ovulation, endometrial thickness, and pregnancy rate.Results: The mean age, duration of infertility, body weight, body mass index, and endocrine status in both the groups were similar at baseline. The total number of follicles during stimulation was statistically significantly greater in the letrozole group (6.81 ± 1.0 vs. 6.1 ± 1.5; P = 0.002). The number of follicles ≥18 mm was statistically significantly higher in the letrozole group compared with the CC group. There was no statistically significant difference in pretreatment endometrial thickness between the two groups, but endometrial thickness at the time of hCG administration was statistically significantly greater in the letrozole group (9.82 ± 0.7 vs. 8.13 ± 0.56; <0.0001). Ovulation occurred in 25 subjects (37.87%) in the letrozole group and 13 (19.67%) in the CC group, with a statistically significant difference between the two groups (P = 0.024). Serum E2 concentrations were statistically significantly lower in the letrozole group (P = 0.001).Conclusion: The effect of letrozole showed a better endometrial response and ovulation rate compared with CC. Letrozole may have a role as a first-line treatment for anovulatory patients with PCOS.