Effects of letrozole on superovulation with gonadotropins in women undergoing intrauterine insemination

Objective: To investigate the effects of letrozole in patients undergoing superovulation with gonadotropins and IUI. Design: Retrospective analysis. Setting: Academic teaching hospital. Patient(s): Women younger than 40 years of age with patent fallopian tubes and infertility of more than I year in duration who were undergoing IUI and gonadotropin therapy. Intervention(s): Gonadotropins alone administered from day 3 or a combination of letrozole, 5 mg/d on day 3 to 7, and gonadotropins starting on day 5 of the menstrual cycle. Ultrasonography was performed before initiation of treatment, on day 9 of menstrual cycle, and as required thereafter until the dominant follicle reached 18 mm in diameter. Ovulation was triggered with 10,000 IU of hCG, and IUI was performed 24 and 48 hours later. Main outcome measure(s): Gonadotropin requirements, endometrial thickness, number of follicles, and pregnancy rate Result(s): All 205 IUI treatment cycles conducted from March 2001 to March 2002 were included. Gonadotropins alone were used in 145 cycles and combination therapy was used in 60 cycles. Patients cotreated with letrozole required fewer gonadotropin administrations (median difference, 300 IU [95% confidence interval (CI), 225-375 IU]), developed more follicles larger than 14 mm (median difference, 1 follicle [95% Cl, 1-2 follicles), and had a thinner endometrium (median difference, 1 mm [95% Cl, 0.4-1.6 mm]). The pregnancy rate did not differ between patients using gonadotropin alone and those using gonadotropin plus letrozole (20.9% vs. 21.6%). Conclusion(s): The addition of letrozole to gonadotropins decreases gonadotropin requirements, increases the number of pre-ovulatory follicles and decreases endometrial thickness, without a negative effect on pregnancy rates. (C) 2003 by American Society for Reproductive Medicine.)