Randomized controlled trial comparing superovulation with letrozole versus recombinant follicle-stimulating hormone combined with intrauterine insemination for couples with unexplained infertility who had failed clomiphene citrate stimulation and intrauterine insemination.

Objective: To compare the efficacy of letrozole to recombinant FSH for ovarian stimulation combined with IUI in a group of patients that had failed to conceive after clomiphene citrate (CC) and IUI.

Design: Prospective randomized trial with human subjects.

Setting: University-based fertility center.

Patient(s): Fifty couples with unexplained infertility that failed to conceive after three cycles of CC combined to IUI.

Intervention(s): Couples were randomized to undergo superovulation either with letrozole or with recombinant FSH combined to IUI.

Main Outcome Measure(s): Clinical pregnancy per cycle of treatment and clinical pregnancy per couple.

Result(s): Pregnancy rate (PR) per cycle was 8.9% in the letrozole group as compared with 14% in the gonadotropin IUI group. This resulted in a cumulative PR per couple of 24% versus 36% and a take home baby rate of 20% versus 28%. Endometrial thickness was significantly lower in the letrozole group (7.1 +/- 2.3 vs 8.6 +/- 1.8).

Conclusion(s): Ovarian stimulation with letrozole is associated with acceptable PRs compared with gonadotropin with significant less cost, risks, and patient inconvenience.