研究開発・学会発表

Study question
This study aimed to evaluate whether a morphokinetic study using time-lapse imaging can predict clinical pregnancy by comparing the time from insemination to cleavage.

Summary answer
Our study shows that the time from insemination to three to four cells (s2) and that to five cells (t5), as observed by the EmbryoScope (Unisense Fertilitech, Denmark), are predictive of clinical pregnancy, but cc2 is not predictive.

What is known already
Several recent publications have shown morphokinetics of embryos by time-lapse imaging as a new method for selecting good quality embryos or clarifying aneuploidy. These findings are based on the time to certain division of embryos. However, each facility used different instruments and cultures in a different manner. We attempted to verify if the criteria that were used by Meseguer (2011) could be used in a more universal situation in the Japanese laboratory.

Study design, size, duration
This study was performed retrospectively. A total of 48 couples (59 embryos) who underwent ICSI and embryo transfer were enrolled in this study from December 2012 to December 2014. The maternal age of participating couples was younger than 38 years, with less than three times of previous unsuccessful IVF.

Participants/materials, setting, methods
Embryos were observed by the EmbryoScope every 15 minutes. We compared the rate of clinical pregnancy between the in-range division group (w/i group) and the out of range division group (w/o group) at each cell division time. This range was based on the definition by Meseguer et al.

Main results and the role of chance
The total rate of pregnancy in all of the participants was 40.1% (24/59). There was no difference in cc2 between the w/i and w/o groups. The s2 w/i group (<0.76 h) had a significantly higher rate of pregnancy (56.5%) than the s2 w/o group (≥0.76h, 30.6%, p=0.048). The t5 w/i group (44.8–56.6 h after insemination) had a significantly higher ratio of obtaining clinical pregnancy (51.4%) than the t5 w/o group (25.0%, p=0.042).

Limitations, reasons for caution
Our results showed a good clinical pregnancy rate using embryos that were selected by time-lapse imaging. This suggests that the criteria of Meseguer using the EmbryoScope are effective for selecting good embryos. However, further clinical studies are required to determine if this method can be used in different environments.

Wider implications of the findings
This study verified the effectiveness of the criteria that were used by Meseguer et al. using a similar instrument and culture conditions. Our study shows that selection of embryos for transfer is possible by time-lapse imaging analysis that was defined by them, even in a different environment.