THE EFFECT OF GONADOTROPIN-RELEASING-HORMONE AGONIST ON EMBRYO QUALITY AND PREGNANCY RATE FOLLOWING CRYOPRESERVATION

Objective: To examine the effect of GnRH analogue (GnRH-a) on the quality of frozen-thawed embryos and the pregnancy rate (PR) resulting from transfer. Design: A retrospective study of two groups of women undergoing transfers of frozen-thawed embryos. In group 1 ovulation induction with hMG was begun after hypophyseal desensitization with GnRH-a for 2 weeks. In group 2 ovulation was induced with hMG only. The freezing and thawing techniques were identical for both groups. Setting: In vitro fertilization unit at a university hospital. Patients: The study group (group 1) included 108 women who underwent 137 transfer cycles of frozen-thawed embryos, and the control group (group 2) included 44 women in 51 cycles of thawed ETs. Interventions: Ovum pick-up and ET techniques were the same for both groups. Methods of embryo freezing and thawing were identical, as were the morphological criteria for grading the embryos. Results: The morphology of embryos was similar in both groups, as was the number of embryos that had at least 50% intact blastomeres (83% +/- 23% and 78% +/- 30% for group 1 and group 2, respectively). The PR (16 of 137 [11.7%] and 6 of 51 [11.8%], respectively) as well as the abortion rate (30%) were similar for both groups. Conclusions: The use of GnRH-a does not affect the quality of embryos nor the pregnancy outcome. Because the yield of frozen embryos per ovum pick-up is higher in cycles stimulated by GnRH-a/hMG, the PR per pick-up cycle is thus anticipated to be higher.