Selection of human blastocysts with a high implantation potential based on timely compaction.

Abstract

Recently, we established a noninvasive system for selecting human blastocysts with a high pre-transfer implantation potential based on first and second division patterns. The present study was carried out to improve the selection system. Embryos that completed first and second divisions within 25.90 and 37.88h after culture, respectively, were selected using a time-lapse incubator. We examined the effects of compaction and blastocyst formation times on pregnancy rates after transferring these embryos at the blastocyst stage. The completion of compaction and blastocyst formation times (79.93 and 97.47h after culture, respectively) of embryos resulting in pregnancies after transfer were significantly (P<0.01) shorter than those (86.46 and 100.34h after culture, respectively) of embryos that failed to induce pregnancies. Embryo selection based on completion of compaction time improved pregnancy rates (40.9 vs. 74.6%, P<0.01). Of the embryos that formed two cells during the first division within 25.90h after culture and four cells during the second division within 37.88h after culture, those that completed compaction within 79.93h after culture before reaching the blastocyst stage had a high implantation potential.