研究開発・学会発表

Background and aims
Using time-lapse imaging, this study aimed to determine if the cleavage time of embryos is useful for selecting good embryos prior to transfer of them to infertile women.

Methods
Development of embryos was recorded and analyzed using EmbryoScope, (Unisense Fertilitech, Denmark). Sixty cycles (maternal age <40 years) of eggs that underwent ICSI or IVF in our clinic were used in this study. The specific time was determined as follows: from two to three cells (cc2), from three to four cells (s2), from insemination to five cells (t5), and to blastocyst formation (sBL). These data were analyzed if these times were in the range of published recommended times. We compared the percentage of the in-range group (w/i group) and the out of range group (w/o group) that achieved clinical pregnancy by the chi-square test.

Results
The t5 w/i group (44.8–56.6 h after insemination) showed a significantly higher ratio of obtaining clinical pregnancy than the w/o group (p=0.024). The sBL w/i group (96.2 h after insemination) had a significantly higher ratio of obtaining clinical pregnancy than the w/o group (p=0.006). There was no difference in time in cc2 and s2 between the w/i and w/o groups.

Conclusion
We conclude that the cleavage time to five cells and the time of initiation at blastocyst formation as shown by time-lapse imaging are important markers for selecting appropriate blastocysts.