Effect of GnRH antagonists in FSH mildly stimulated intrauterine insemination cycles: a multicentre randomized trial.

BACKGROUND The usefulness of GnRH antagonists in mild controlled ovarian hyperstimulation (COH) and intrauterine insemination (IUI) cycles is debated. METHODS Two-hundred and ninety-nine couples with unexplained or mild male factor infertility were enrolled in this international multicentre randomized controlled trial. Women allocated to the GnRH antagonist group (n=148) received 50 IU recombinant FSH starting on day 3 of the menstrual cycle and Ganirelix 0.25 mg daily starting from the day in which a follicle with a mean diameter of 13-14 mm was visualized at ultrasound. Women allocated to the control group (n=151) were administered only 50 IU recombinant FSH starting on day 3 of the menstrual cycle. Couples were recruited only for their first treatment cycle. The primary outcome was the clinical pregnancy rate per initiated cycle. RESULTS Baseline characteristics of the two treatment groups were similar. Clinical pregnancy rates per initiated cycle in women who did and did not receive GnRH antagonists were 12.2 and 12.6%, respectively (P=1.00). The relative risk of conception (95% confidence interval) for the use of GnRH antagonists was 1.0 (0.5-1.9). CONCLUSIONS In mild COH and IUI cycles, any benefit of the use of GnRH antagonists in improving pregnancy rates is <2-fold increase.