Day 5 expanded blastocysts transferred on same day have comparable outcome to those left for more extended culture and transferred on day 6

Abstract

Objective To study the outcome of blastocysts showing expansion on day 5 and transferred on day 5 or 6, in comparison with those unexpanded and transferred on day 6. Study Design Prospective cohort of 221 women prepared for BET classified into three groups according to timing of blastocyst expansion and day of embryo transfer. Group I; with expanded blastocysts on day 5 having day 5 transfer, group II; with expanded blastocysts on day 5 having day 6 transfer and group III ; with delayed expansion undergoing day 6 BET. Results Implantation rates, pregnancy rates, ongoing pregnancy rates, and live birth rates in the first 2 groups were almost double the rates in the third group. The figures for implantation rates were 40 % in the first two groups vs. 19 % in the third group (P<0.05). Pregnancy rates were 60.9 % and 64 % vs. 31.8 % (P<0.05) and ongoing pregnancy/ live-birth rates were 52.3 % & 56 % vs. 27.3 %. Conclusion The current study reports better implantation and pregnancy rates with earlier expanding blastocysts regardless of the time of transfer.

Comparison of clinical outcomes between single and double vitrified-warmed blastocyst embryo transfer according to the day of vitrification

“…However, their study had a disadvantage of a small number of patients who were transferred on day 6. Our study which included more than 100 cycles in 6d-SVBT was consistent with the study by Elgindy and Elsedeek [5]. However, our study also has important disadvantages of having younger patients in the 5d-SVBT group than those in the 6d-SVBT group (31.8±2.8 vs. 32.4±2.7, p =0.023).…”

“…These differences in clinical outcomes between fresh and frozen-thawed cycles maybe due to the speed of development of blastocysts and/or endometrial receptivity according to the date of embryo transfer. In relation to these issues, Elgindy and Elsedeek [5] reported that blastocysts developed on day 5 had comparable implantation and pregnancy rates whether transferred on day 5 or day 6, whereas the pregnancy rate of expanded blastocysts on day 5 regardless of the time of transfer was significantly higher than that of expanded blastocysts on day 6. They concluded that clinical outcomes were affected by the speed of development of blastocysts rather than endometrial receptivity.…”

Comparison of aneuploidy, pregnancy and live birth rates between day 5 and day 6 blastocysts

“…Conversely, current research that transferred patients on day 5 and on day 6, regardless of day of blastulation found no difference in pregnancy and implantation rates (Elgindy and Elsedeek, 2012).…”

Delayed blastulation, multinucleation, and expansion grade are independently associated with live-birth rates in frozen blastocyst transfer cycles

“…Perhaps one of the most controversial questions is the developmental competency of embryos with delayed blastulation. Fresh blastocyst transfer data indicate that slow growing embryos not blastulating until day 6 have lower pregnancy potential (9,10,21). The close relationship between timely cell division and developmental competence is further supported by kinetic data from time-lapse culture systems (4,6,7).…”