Clomiphene citrate or letrozole for ovulation induction in women with polycystic ovarian syndrome: a prospective randomized trial

ObjectiveTo compare the effects of letrozole (5 mg) and clomiphene citrate (100 mg) for ovulation induction in women with polycystic ovary syndrome (PCOS).DesignProspective randomized trial.SettingUniversity teaching hospital and private practice setting.Patient(s)The study comprised a total of 438 infertile women (1063 cycles) with PCOS.Intervention(s)Patients were randomized to treatment with 5 mg of letrozole daily (218 patients, 545 cycles) or 100 mg of clomiphene citrate daily (220 patients, 518 cycles) for 5 days starting on day 3 of menses. Timed intercourse was advised 24 to 36 hours after hCG injection.Main Outcome Measure(s)Number of follicles, serum estradiol, serum progesterone, endometrial thickness, and pregnancy and miscarriage rates.Result(s)The mean age, parity, and duration of infertility in both groups were similar. The total number of follicles was statistically significantly greater in the clomiphene citrate group (6.8 ± 0.3 versus 4.4 ± 0.4). Endometrial thickness at the time of hCG administration was statistically significantly greater in the CC group (9.2 ± 0.7 mm versus 8.1 ± 0.2 mm). The duration to reach a dominant follicle was statistically significantly longer in the letrozole group (12.1 ± 1.3 versus 8.8 ± 2.9 days). Ovulation occurred in 365 out of 540 cycles (67.5%) in letrozole group and 371 out of 523 cycles (70.9%) without a statistically significant difference. Levels of serum estradiol and progesterone were statistically significantly higher in the clomiphene citrate group. The pregnancy rate per cycle was 15.1% in the letrozole group and 17.9% in the clomiphene citrate group without statistically difference between the groups.Conclusion(s)The results of this study did not show any advantage to the use of letrozole over clomiphene citrate as a first-line treatment for induction of ovulation in women with PCOS.