Effect of letrozole at 2.5 mg or 5.0 mg/day on ovarian stimulation with gonadotropins in women undergoing intrauterine insemination

Objective

To determine the effect of combined therapy of letrozole (2.5 mg or 5.0 mg) with recombinant follicle-stimulating hormone (FSH) in comparison with the administration of recombinant FSH alone in an intrauterine insemination (IUI) program.

Design

Retrospective study.

Setting

Assisted fertilization program in a specialized infertility center.

Patient(s)

110 women undergoing IUI and gonadotropin therapy.

Intervention(s)

Recombinant FSH alone administered from day 3 or combined with letrozole, 2.5 or 5.0 mg/day, on days 3 to 7, and gonadotropins starting on day 7 of the menstrual cycle. Transvaginal ultrasound examinations were done until the dominant follicle reached 18 mm in diameter. Ovulation was triggered with 10,000 IU of human chorionic gonadotropin (hCG), and IUI performed 30 to 40 hours later.

Main Outcome Measure(s)

Recombinant FSH dose required, number of follicles greater than 14 mm and 18 mm, endometrial thickness, pregnancy rates, miscarriages, and characteristics of newborns.

Result(s)

Women treated with FSH and 5.0 mg/day of letrozole required a lower dose of FSH than the group cotreated with 2.5 mg/day of letrozole or with FSH alone. Throughout most of the follicular phase, the endometrial thickness was statistically significantly less in both letrozole cotreatment groups compared with the FSH control group. By the day of hCG administration, the endometrial thickness was comparable among all the groups. The pregnancy rates were the same with recombinant FSH alone or combined with letrozole.

Conclusion(s)

In terms of cost-effectiveness, 5.0 mg/day of letrozole is more effective than the 2.5 mg/day in cotreatment with no adverse effect on pregnancy rate or outcome.

Key Words: Letrozole, aromatase inhibitors, recombinant FSH, intrauterine insemination