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Preferable correlation to blastocyst development and pregnancy rates with a new embryo grading system specific for day 3 embryos.

Nomura M, Iwase A, Furui K, Kitagawa T, Matsui Y, Yoshikawa M, Kikkawa F

, Cinic Mama 3-34-1 Imajyuku, Ogaki, 503-0807, Japan.

Purpose: To investigate the cleavage stage embryo quality by the correlation between the morphological features and blastocyst development rate to develop a new embryo grading system. Methods: A retrospective analysis, including 216 cycles of cleavage stage embryo transfer and 251 cycles of blastocyst transfer. The correlation with blastocyst development of the embryo cleavage stage, fragmentation and uniformity of blastomeres was evaluated. Results: There were significant differences in the blastocyst development rate between >/=7 cells and </=6 cells (68.8% vs. 30.7%), <50% fragmentation and >/=50% fragmentation (51.9% vs. 25.7%), and evenly sized blastomeres and unevenly sized blastomeres (48.7% vs. 30.1%) on day 3. The new grading system defined by these 3 parameters showed a preferable correlation to the pregnancy rate. Conclusions: The new grading system specific for day 3 embryos is useful for the selection of good quality embryos and may improve the pregnancy rate.

Published 11 January 2007 in J Assist Reprod Genet.
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