A prospective randomised study comparing a GnRH-antagonist versus a GnRH-agonist short protocol for ovarian stimulation in patients referred for IVF

Objective: To compare two short protocols for ovarian stimulation in IVF cycles using an antagonist and an agonist short protocol. The outcomes studied were dosis rec FSH needed, days of stimulation, number of oocytes retrieved and pregnancy outcome. Methods: A prospective randomised study design. Inclusion criteria: first or second IVF attempt in women younger than 40 years. In the agonist protocol (Suprefact®) nasal spray was used. In the antagonist protocol (Orgalutran)® was started as soon as at least 1 follicle of 12 mm was visualized on ultrasound. Results: 160 cycles were included in the study: 80 in the antagonist group and 80 in the agonist group. A higher dosis of recombinant FSH (rec FSH) was used for stimulation in the antagonist group (1897 IU versus 1655 IU). Pregnancy rate per ET in the antagonist group was 37% with an ongoing pregnancy rate of 21%/ET and an implantation rate of 22%; versus respectively 39%, 20% and 22% in the agonist treated group. Live birth rate per started cylce was 19% in the antagonist group versus 20% in the agonist group. Conclusion: This study shows that implantation rates, ongoing pregnancy rates and live birth rates are equal in both groups. An identical number of oocytes was retrieved, with no difference in duration of the stimulation although a higher dosis of rec FSH was needed in the antagonist group.