Abstract
OBJECTIVE: To investigate whether delaying the start of ovarian stimulation with GnRH antagonist improves ovarian response in poor responders. DESIGN: Retrospective study. SETTING: Academic medical center. PATIENT(S): Thirty patients, who responded poorly and did not get pregnant with conventional estrogen priming antagonist IVF protocol. INTERVENTION(S): Delayed-start antagonist protocol (estrogen priming followed by early follicular-phase GnRH antagonist treatment for 7 days before ovarian stimulation). MAIN OUTCOME MEASURE(S): Number of dominant follicles and mature oocytes retrieved, mature oocyte yield, and fertilization rate. RESULT(S): The number of patients who met the criteria to proceed to oocyte retrieval was significantly higher in the delayed-start protocol [21/30 (70%)] compared with the previous conventional estrogen priming antagonist cycle [11/30 (36.7%)]. The number of dominant follicles was significantly higher in the delayed-start (4.2 ± 2.7) compared with conventional (2.4 ± 1.3) protocol. In patients who had oocyte retrieval after both protocols (n = 9), the delayed start resulted in shorter ovarian stimulation (9.4 ± 1.4 days vs. 11.1 ± 2.0 days), higher number of mature oocytes retrieved (4.9 ± 2.0 vs. 2.2 ± 1.1), and a trend toward increased fertilization rates with intracytoplasmic sperm injection (ICSI; 86 ± 17% vs. 69 ± 21%) compared with conventional protocol. After delayed start, the average number of embryos transferred was 2.8 ± 1.4 with implantation rate of 9.8% and clinical pregnancy rate of 23.8%. CONCLUSION(S): The delayed-start protocol improves ovarian response in poor responders by promoting and synchronizing follicle development without impairing oocyte developmental competence.