Ovarian stimulation in in vitro fertilization with or without the "long" gonadotropin-releasing hormone agonist protocol: effect on cycle duration and outcome.

OBJECTIVE To study the correlation between stimulation duration of IVF cycles, with and without GnRH agonist (GnRH-a), and cycle outcome. DESIGN Retrospective analysis of data. SETTING University-affiliated IVF clinic. PATIENT(S) 998 IVF cycles in which long GnRH-a protocol was used, and 155 cycles with hMG only. INTERVENTION(S) IVF cycles. MAIN OUTCOME MEASURE(S) Cycle outcome in number of oocytes and embryos, and pregnancy rate. RESULT(S) The mean stimulation duration (+/-SD) was 9.6+/-1.7 and 6.7+/-1.0 for the GnRH-a and the hMG-only cycles, respectively (P<0.01). In the GnRH-a group, no statistically significant correlation between cycle duration and pregnancy rate was found. Interestingly, the patients treated for 9 days had the highest number of oocytes retrieved and the highest pregnancy rate. Stimulation duration was not affected by age in either protocol. GnRH-a cycles yielded a significantly higher number of oocytes and embryos compared to cycles without GnRH-a. The pregnancy rate was similar in both groups. CONCLUSION(S) Stimulation duration in the long GnRH-a protocol group was significantly longer than in the hMG-only group. Stimulation duration was not affected by age. No statistically significant correlation was found between stimulation duration and cycle outcome in the long protocol group.