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.