Objective: To use gonadotropin-releasing hormone agonist (GnRH-a) instead of human chorionic gonadotropin (hCG) to induce oocyte maturation for in vitro fertilization (IVF).

Design: Pituitary and ovarian responses to GnRH-a and the outcome of IVF were studied prospectively. Data from patients injected with hCG were analyzed retrospectively.

Setting: Program of IVF at the Rambam (Governmental) Hospital, Haifa, Israel.

Patients and interventions: One or two doses of buserelin acetate 250 to 500 micrograms were administered to six patients with moderate response (Estradiol [E2], 1,494 +/- 422 [+/- SD] pg/mL) and 8 patients with exaggerated response (E2, 7,673 +/- 3,028 pg/mL) to gonadotropin stimulation. Progesterone (P) and E2 were administered for luteal support.

Main outcome measures: Gonadotropin-releasing hormone agonist effectively triggered luteinizing hormone (LH)/follicle-stimulating hormone (FSH) surge. Mature oocytes were recovered in all patients. Luteal E2 and P were lower than in patients injected with hCG. No signs of ovarian hyperstimulation syndrome were observed.

Results: Serum LH and FSH rose over 4 and 12 hours, respectively, and were significantly (P less than 0.05) elevated for 24 hours. Of all mature oocytes, 67% fertilized and 82% cleaved. Four pregnancies were obtained.

Conclusions: A bolus of GnRH-a is able to trigger an adequate midcycle LH/FSH surge, resulting in oocyte maturation and pregnancy. Our preliminary results also suggest that it allows a more accurate control of ovarian steroid levels during the luteal phase and may prevent the clinical manifestation of ovarian hyperstimulation syndrome.