研究開発・学会発表

【Objective】
The objective of this study is to examine the clinical significance of blastocyst grade at post-thawing.

【Design】
Retrospective case-control study

【Materials and Methods】
In this study, we collected data from the patients who underwent single frozen-thawed blastocyst transfer in hormone-replacement cycle at our clinic. We included a total of 2425 cycles from January 2011 to December 2012. We evaluated blastocyst grade before vitrification and after thawing according to Gardner’s classification and examined CPR (clinical pregnancy rate) and DR (delivery rate).

【Results 】
The results are summarized in Table 1.
As a total, 38.6% of the blastocysts revealed equivalent grade both at pre-freezing and post-thawing, 39.0% of the blastocysts decreased their grade and 22.4% of blastocysts increased their quality at post-thawing observation. In the group of blastocysts those increased their morphological grade after thawing, CPR and DR tended to be high when it compares to the group of blastocysts those decreased their grade after thawing. This tendency was common irrespective of the grade at pre-freezing.

【Conclusions】
The degree of post-thaw recovery of blastocyst could be one of the predictive factors for CPR and DR in frozen-thawed blastocyst transfer. Viable blastocysts may recover their quality during freeze-thaw process.

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