Day5形成囊胚: 染色體正常率約67%
Day6形成囊胚: 染色體正常率約52%
Day7形成囊胚: 染色體正常率約43%

Hum Reprod. 2019 Aug 12. pii: dez138. doi: 10.1093/humrep/dez138. [Epub ahead of print]

Worth the wait? Day 7 blastocysts have lower euploidy rates but similar sustained implantation rates as Day 5 and Day 6 blastocysts.

Tiegs AW1,2, Sun L3, Patounakis G4, Scott RT1,2.

Author information

1

Instituto Valenciano de Infertilidad - Reproductive Medicine Associates (IVI-RMA), Basking Ridge, NJ, USA.

2

Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.

3

Foundation for Embryonic Competence (FEC), Basking Ridge, NJ, USA.

4

Reproductive Medicine Associates of Florida, Orlando, FL 32746, USA.

Abstract

STUDY QUESTION:

Does the reproductive potential of embryos change when blastocyst development takes longer than the traditionally accepted 5 days when accounting for aneuploidy and endometrial-embryo asynchrony?

SUMMARY ANSWER:

Aneuploidy increases with increasing duration of blastulation, but if blastocyst morphologic quality and endometrial-embryo asynchrony are controlled for, euploid Day 7 embryos have similar sustained implantation as compared to Days 5 and 6 euploid blastocysts.

WHAT IS KNOWN ALREADY:

The relative contributions of diminished embryo quality versus endometrial and embryo asynchrony to poor outcomes associated with embryos cultured past Day 6 are not clear. Asynchrony can be eliminated by embryo vitrification with transfer in a subsequent month after retrieval.

STUDY DESIGN, SIZE, DURATION:

Retrospective cohort study of patients from a single center attempting conception through ICSI and utilizing preimplantation genetic testing for aneuploidy screening (PGT-A) from January 2017 to September 2018. Cycles were excluded if they utilized surgical sperm or preimplantation genetic testing for monogenetic/single gene defects. ICSI cycle outcomes from 2586 patients were evaluated for ploidy status of embryos.

PARTICIPANTS/MATERIALS, SETTING, METHODS:

Only patients undergoing single, euploid frozen embryo transfer were included when analyzing cycle outcomes by day of blastocyst expansion of the transferred embryo (n = 2130). Ploidy rates by the day upon which an embryo was considered to be usable (denoted, 'usable blastulation day') were determined so as to assess the contribution of aneuploidy to slow embryo development. Outcomes of euploid frozen single embryo transfers (SET) of Day 7 embryos were evaluated to assess the reproductive potential associated with embryos that were slowly developing for reasons other than aneuploidy. Analyses were adjusted by maternal age and blastocyst morphology.

MAIN RESULTS AND THE ROLE OF CHANCE:

Overall, 67.7% (n = 3508) of usable Day 5 blastocysts were euploid, 52.1% (n = 5560) of usable Day 6 blastocysts were euploid and 43.1% (n = 229) of usable Day 7 embryos were euploid (Day 5 versus Day 6: odds ratio (OR) 0.7 (95% CI, 0.64-0.76), P < 0.001; Day 5 versus Day 7: OR 0.56 (95% CI, 0.46-0.69), P < 0.001; Day 6 versus Day 7: OR 0.81 (95% CI, 0.67-0.99), P = 0.036). Stratified by Society for Assisted Reproductive Technology maternal age groups, a reduction in the prevalence of euploidy by increasing time to embryo blastulation was still seen. The sustained implantation rate (SIR) was similar after euploid SET of Days 5 and 6 embryos (overall, 68.9% (95% CI, 66.0-71.6) and 66.8% (95% CI, 63.8-69.7), respectively; P = 0.81). SIR after euploid Day 7 SET appeared slightly lower than that of Days 5 and 6 embryos (52.6% (95% CI, 35.8-69.0); (Day 5 versus Day 7: OR, 0.67 (95% CI, 0.32-1.41), P = 0.29; Day 6 versus Day 7: OR 0.58 (95% CI, 0.28-1.2), P = 0.14)) but did not achieve statistical significance.