Use of letrozole versus clomiphene citrate combined with gonadotropins in intrauterine insemination cycles: a pilot study

ObjectiveTo compare the clinical outcomes between letrozole and clomiphene citrate (CC) in gonadotropin-combined intrauterine insemination (IUI) cycles.DesignProspective pilot study.SettingOne university hospital and two private infertility clinics.Patient(s)Ninety-three infertile couples eligible for superovulation and IUI.Intervention(s)A letrozole dose of 2.5 mg/day (n = 66) or a CC dose of 100 mg/day (n = 27) was given on day 3–7 of the menstrual cycle, combined with human menopausal gonadotropin (hMG) at a dose 150 IU every other day starting on day 5.Main Outcome Measure(s)The number of mature follicles, serum estradiol (E2) and progesterone (P) levels, endometrial thicknesses on the day of human chorionic gonadotropin (hCG), and clinical pregnancy rates.Result(s)The patients’ clinical characteristics were comparable between the two groups. The number of mature follicles (3.2 ± 1.7 vs. 5.6 ± 2.4) and serum E2 levels on the day of hCG (231.0 ± 179.8 vs. 1,371.7 ± 750.5 pg/mL) were significantly lower in the letrozole group. No significant differences were found in endometrial thickness measured on the day of hCG or clinical pregnancy rates (18.2% vs. 25.9%). The rate of patients with serum P levels >1.0 ng/mL on the day of hCG was significantly lower in the letrozole group (4.5% vs. 25.9%).Conclusion(s)Letrozole produced a comparable pregnancy rate vs. CC in gonadotropin-combined IUI cycles. Our results should be confirmed in larger populations with proper randomization.