Frozen blastocysts: Assessing the importance of day 5/day 6 blastocysts or blastocyst quality

Abstract

The aim of the present study was to analyze the high-quality blastocyst (HB) rate in all embryo frozen cycles and investigate the pregnancy outcomes for day 5/day 6 (D5/D6) blastocysts with respect to the blastocyst quality in programmed single vitrified-warmed blastocyst transfer (SVBT). We performed a retrospective study comparing D5/D6 HBs in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) for all blastocyst frozen cycles. Patients were <35 years at the oocyte collection in their first fresh cycle without fresh transfer. A total of 1,560 IVF/ICSI cycles and 5,328 blastocysts were analyzed. The IVF HB rate was higher than that of ICSI (52.7% vs. 42.6%; P<0.05). The D5 HB rate was much higher than the D6 HB rate (61.6% vs. 29.4%; P<0.05). There were 22.4% (349/1,560) cycles that only had D6 blastocysts, of which IVF cycles were lower than ICSI (19.8% vs. 28.5%; P<0.05). The clinical pregnancy rate and implantation rate in the D5 group were significantly higher than these rates in the D6 group (57.4% vs. 46.2%, 58.9% vs. 47.3%; P<0.05). However, the clinical pregnancy rate and implantation rate of the D5 HBs were not significantly different from those of the D6 HBs (60% vs. 54.5%, 62% vs. 56.3%; P>0.05). In conclusion, the fertilization method (IVF/ICSI) directly influences the HB rate and blastocyst development rates. When we controlled for patient age, transfer frequency, and endometrium on day 5, it was not the development stage (D5/D6), rather the transfer blastocyst quality that played an important role in pregnancy outcomes.

Prolonging the time of progesterone supplementation to improve the pregnancy outcomes of single day 6 blastocyst transfer in frozen-thawed cycles: study protocol for a randomized controlled trial

“…Recently, retrospective cohort studies concluded that the clinical pregnancy, implantation, and LBR after frozen-thawed blastocyst transfer are significantly higher in D5 embryos than in D6 embryos [ 9 , 10 ]. However, some studies found no significant difference between day 5 and day 6 frozen-thawed blastocysts, with similar clinical pregnancy, implantation, and birth rates [ 11 , 12 ].…”

Pregnancy outcome and follow-up of offspring of donor oocytes recipient from PCOS patients

“…The blastocyst was then moved at room temperature (22–25 °C) to Kitazato (Japan) equilibration solution (ES). After 6–8 min, the blastocyst was quickly washed in vitrification solution (VS) for 45–60 s and transferred onto the straw (Kitazato Japan) using a micropipette and immersed vertically into liquid nitrogen [ 12 ].…”

“…After 1 or 2 h of culture the embryo was reassessed again and often the re-expansion of the blastocoel was reported; this indicated that the embryo physiologically survived the warming procedure. Embryo transfer was normally performed within 2 or 3 h. All programmed warmed cycles, both at D5 and D6, were transferred in D5 endometrium [ 12 ].…”

Comparing the pregnancy outcomes of fresh and frozen embryo transfer after early rescue ICSI

“…The blastocyst was then moved at room temperature (22-25°C) to Kitazato (Japan) equilibration solution (ES). After 6-8 min, the blastocyst was quickly washed in vitri cation solution (VS) for 45-60s and transferred onto the straw (Kitazato Japan) using a micropipette and immersed vertically into liquid nitrogen (Jiang et al 2022).…”

“…Clinical outcome B ultrasound was used to observe the gestational sac and fetal heart at 35 days after implantation was diagnosed as clinical pregnancy. Implantation rate was de ned as the ratio of the number of gestational sacs and fetal heart observed under B ultrasound and the number of transferred embryos (Jiang et al 2022). The clinical pregnancy rate, implantation rate, ectopic pregnancy, abortion rate and live birth rate were analyzed.…”