Day 5 vitrified blastocyst transfer versus day 6 vitrified blastocyst transfer in oocyte donation program

Abstract

The superiority of day 5 blastocysts compared to day 6 blastocysts in fresh cycle transfers was previously demonstrated and attributed mainly to endometrial asynchrony. Data from frozen blastocysts transfers showed conflicting results, possibly due to heterogeneous patient population and embryo quality. The aim of this study was to compare clinical pregnancy rate (CPR) and live birth rate (LBR) between transfers of vitrified day 5 blastocysts and day 6 blastocysts in oocyte donation, blastocyst-only cycles. In a retrospective, multi-center study, with a single oocyte donation program, a total of 1840 frozen embryo transfers (FET’s) were analyzed, including 1180 day 5 blastocysts and 660 day 6 blastocysts transfers. Day 5 blastocyst transfers had better embryonic development and significantly higher CPRs (34.24% vs. 20.15%, P < 0.0001), higher LBRs (26.89% vs. 14.77%, P < 0.0001), less cycles to LBR (1.83 ± 0.08 vs. 2.39 ± 0.18, P = 0.003) and shorter time to LBRs (76.32 ± 8.7 vs. 123.24 ± 19.1 days, P = 0.01), compared to day 6 transfers, respectively. A multivariate stepwise logistic regression indicated, that day 5 transfer was an independent factor for CPRs (OR 1.91; 95% CI 1.43–2.54, P < 0.001) and LBRs (OR 2.26; 95% CI 1.19–4.28, P = 0.01), regardless of embryo quality, compared to day 6. In conclusion, day 5 blastocysts in oocyte donation program have significantly higher CPRs and LBRs, and present shorter time to delivery, compared to day 6 blastocysts, regardless of embryo quality.

Analysis of Biochemical and Clinical Pregnancy Loss Between Frozen-Thawed Embryo Transfer of Blastocysts and Day 3 Cleavage Embryos in Young Women: A Comprehensive Comparison

“…Therefore, when comparing the rate of BPL or CPL between transfer of blastocysts and Day 3 cleavage embryos, the quality of embryos transferred, including blastocysts or cleavage embryos, should be taken into consideration. Our study suggested that morphologically good Day 5 blastocysts should be first considered for transfer, not only because of the high implantation potential, as a previous study reported (45), but also because of the low rate of pregnancy loss. Furthermore, our study may help to explain a recently published study indicating that FET cycles with blastocysts arising from poor-quality cleavage embryos showed a significantly higher miscarriage rate (46).…”

No advantage of single day 6 good-quality blastocyst transfer versus single day 5 poor-quality blastocyst transfer in frozen-thawed cycles stratified by age: a retrospective study

“…When transferring the same quality blastocysts, the live birth rate of D5 blastocysts in FET cycles was still significantly higher than that of D6 blastocysts [ 9 , 20 ]. Additionally, Yerushalmi et al found that D5 blastocysts in the oocyte donation program resulted in significantly better clinical outcomes and shorter time to delivery than D6 blastocysts, regardless of embryo quality [ 21 ]. One potential mechanism is that blastocyst developmental speed is associated with the incidence of abnormal spindle morphology.…”

Does Trophectoderm Mitochondrial DNA Content Affect Embryo Developmental and Implantation Potential?

“…These results are consistent with findings of other research teams [ 29 , 33 , 44 , 45 ]. As day 5 blastocysts are considered to provide higher implantation rates [ 51 , 52 , 53 , 54 ], higher mtDNA content may be associated with embryo developmental potential. Additionally, we confirmed the association between Ms and the day of TE biopsy in successfully implanted embryos.…”