GnRH-agonist down-regulation is not essential for the success of frozen embryo transfers

Abstract

OBJECTIVE: To compare outcomes of frozen-thawed embryo transfer (FET) cycles prepared with or without GnRH down-regulation prior to and during endometrial preparation. DESIGN: A retrospective analysis of two protocols for endometrial preparation during FET cycles. MATERIALS AND METHODS: Between Sept. 2005 and Feb. 2008, GnRHa was used during endometrial preparation (group 1, 102 cycles). Briefly, administration of Lupron 1 mg daily began during the mid-luteal phase and of Estradiol Valerate (EV) 2 to 4 mg every-other-day intramuscularly (IM) began at day-5 of the following menstrual cycle. When endometrial thickness reached ≥8mm, Lupron was discontinued and progesterone in oil 100mg daily was administered IM together with the EV. Embryos were transferred on the 6th day of progesterone administration. Between Feb. 2008 and Dec. 2009, GnRHa was omitted (group 2, 94 cycles). Pregnancy outcomes were compared between these two protocols. RESULTS: Mean patient age (35.0 ± 5.46 vs 35.1 ± 5.38) was not different between group 1 and 2. FET cycles in group 1 had slightly thicker maximal endometrium (11.37 ± 1.58 mm) than in group 2 (10.97 ± 1.45 mm, P=0.004). Also more embryos were transferred in group 1 than in group 2 (2.21 ± 0.57 vs 2.04 ± 0.50, P=0.03). Clinical pregnancy, ongoing pregnancy rates (64.1% vs 57.9% and 57.3% vs 51.6% respectively) were slightly higher in the group 1 than in group 2, but there were no statistical significances (P>0.05). The implantation rate (35.5% vs 36.1%, P>0.05) was slightly lower in group 1 than in group 2. Furthermore, very few cycles exhibited follicular growth during endometrial preparation for both protocols and there were no mature follicles at the onset of progesterone administration in either group. CONCLUSION: GnRHa down-regulation prior to and during endometrial preparation for FET is not beneficial and may be omitted for routine frozen embryo transfer cycles. The slightly lower pregnancy outcome in the non-GnRHa group is most likely the result of slightly fewer embryos transferred in this group.