P-41: Effects of ovulation during endometrial preparation on the outcomes of cryopreserved-thawed blastocyst transfer cycles

Abstract

Blastocyst transfer provides the ability to reduce the incidence of high order multiple pregnancy while optimizing pregnancy rates. Cryopreserved-thawed blastocyst transfer significantly may improve cumulative pregnancy rate. Cryopreserved-thawed embryo transfer has been successfully performed in ovulatory cycles such as natural cycles or ovulation induction cycles, and in non-ovulatory cycles in which the endometrium is artificially prepared with exogenous hormone supplementation. However, there are few available reports on the impact of ovulation during endometrial preparation in cryopreserved-thawed embryo transfer cycles. We compared clinical outcomes between ovulatory and non-ovulatory cycles to evaluate whether ovulation affected the outcomes during endometrial preparation in cryopreserved-thawed blastocyst transfer cycles. Prospective observational study. Sixty-eight patients who underwent cryopreserved-thawed blastocyst transfer from Jun 2005 to Mar 2006 were included in this study and divided into two groups: non-ovulatory group (n=33) and ovulatory group (n=35). In non-ovulatory group, endometrial preparation was achieved by oral estradiol valerate and intramuscular progesterone without prior gonadotropin-releasing hormone agonist suppression. Ovulatory group included natural cycles (n=17) and ovulation induction cycles using clomiphene citrate (n=9) or letrozole (n=9). We compared clinical characteristics and pregnancy outcomes, which were statistically analyzed using Mann-Whitney U-test and Fisher’s exact test where appropriate. The duration of endometrial preparation was significantly shorter in ovulatory group compared to non-ovulatory group (14.6±1.3 days vs. 13.9±1.7 days, p=0.042). Although there was no significant difference in the mean endometrial thickness on the day of progesterone or hCG administration between the two groups, triple endometrial patterns were more frequently observed in ovulatory group (18/33 (54.5%) vs. 30/35 (85.7%), p=0.007). However, there were no significant differences between the two groups with regard to the implantation and clinical pregnancy rates per embryo transfer.Tabled 1Tabled 1 These findings suggest that ovulation during endometrial preparation does not have any significant effect on the pregnancy outcomes. Both ovulatory and non-ovulatory cycles may be equally effective for endometrial preparation in cryopreserved-thawed blastocyst transfer cycles.