Related Experiment Video
Updated: Mar 22, 2026
Morphometric Protocol for the Objective Assessment of Blastocyst Behavior During Vitrification and Warming Steps
Published on: February 28, 2019
The effects of blastocyst morphological score and blastocoele re-expansion speed after warming on pregnancy outcomes
Huiqun Yin1, Hong Jiang1, Ruibing He1
1Reproductive Medicine Center, 105th Hospital of PLA, Hefei, China.
Objective:
The aim of this study was to investigate associations between the morphology score of blastocysts and blastocoele re-expansion speed after warming with clinical outcomes, which could assist in making correct and cost-effective decisions regarding the appropriate time to vitrify blastocysts and to transfer vitrified-warmed blastocysts.
Methods:
A total of 327 vitrified-warmed two-blastocyst transfer cycles in women 38 years old and younger were included in this retrospective study.
Results:
The clinical pregnancy rate (CPR) and implantation rate (IR) of transfers of two good-morphology grade 4 blastocysts vitrified on day 5 (64.1% and 46.8%, respectively) were significantly higher than the CPR and IR associated with the transfers of two good-morphology grade 3 blastocysts vitrified on day 5 (46.7% and 32.2%, respectively). No significant differences were found in the CPR and IR among the transfers of two good-morphology grade 4 blastocysts regardless of the day of cryopreservation. Logistic regression analysis showed that blastocoele re-expansion speed after warming was associated with the CPR.
Conclusion:
The selection of a good-morphology grade 4 blastocyst to be vitrified could be superior to the choice of a grade 3 blastocyst. Extending the culture of grade 3 blastocysts and freezing grade 4 or higher blastocysts on day 6 could lead to a greater likelihood of pregnancy. Since re-expansion was shown to be a morphological marker of superior blastocyst viability, blastocysts that quickly re-expand after warming should be prioritized for transfer.
