Ovarian response and pregnancy rates in in vitro fertilization, gamete intrafallopian transfer, and in vivo fertilization therapies after combined gonadotropin-releasing hormone agonist/human menopausal gonadotropin stimulation.

Ovarian stimulation cycles were initiated using human menopausal gonadotropin (HMG) in 318 women (643 cycles) without pretreatment and in 341 women (525 cycles) after pituitary desensitization by pretreating with the gonadotropin-releasing hormone agonists (GnRH-A) buserelin acetate or triptorelin acetate. Significantly higher pregnancy rates were observed in the GnRH-A/HMG group (15%) as compared to the HMG group (7%) following in vitro (p less than 0.05) but not in vivo fertilization therapy (14 vs. 9%, respectively). After in vitro fertilization, the rates increased with increasing length of the active phase of follicular maturation. Gamete intrafallopian transfer, performed only in the GnRH-A/HMG group, led to a pregnancy rate of 34%. Overall, there was a clear trend to higher pregnancy rates in the GnRH-A/HMG group (16%) as compared to the HMG group (8%). Abortion rates were comparable in both groups (24 vs. 19%). The higher pregnancy rates in the GnRH-A/HMG group were attributable to enhanced follicular maturation and optimized ovarian stimulation produced by the hypogonadotropic state. However, an increased risk of the ovarian hyperstimulation syndrome was observed in these patients.