Sibling oocytes cultured in a time-lapse versus benchtop incubator: how time-lapse incubators improve blastocyst development and euploid rate

The aim was to study whether a limited exposure of embryos outside the incubator has an effect on embryo development, blastocyst quality and euploid outcomes. This retrospective study was performed at ART Fertility Clinics, Abu Dhabi, United Arab Emirates (UAE) between March 2018 and April 2020 and included 796 mature sibling oocytes that were split randomly between two incubators after intracytoplasmic sperm injection (ICSI): an EmbryoScope (TM) (ES) incubator and a benchtop incubator, G185 K-SYSTEMS (KS). The fertilization, cleavage, embryo/blastocyst qualities, useable blastocyst and euploid rates were assessed to evaluate the incubator performance. In total, 503 (63.2%) mature oocytes were cultured in the EmbryoScope and 293 (36.8%) in the K-SYSTEMS. No differences were observed in fertilization rate (79.3% vs 78.8%, P = 0.932), cleavage rate (98.5% vs 99.1%, P = 0.676) and embryo quality on Day 3 (P = 0.543) between both incubators, respectively. Embryos cultured in the EmbryoScope, had a significantly higher chance of being biopsied (64.8% vs 49.6%, P < 0.001). Moreover, a significantly higher blastocyst biopsy rate was observed on Day 5 in the EmbryoScope (67.8% vs 57.0%, P = 0.037), with a highly significant increased euploid rate (63.5% vs 37.4%, P = 0.001) and improved blastocyst quality (P = 0.008). We found that exposure of embryos outside the incubator may negatively affect the in vitro blastocyst development and euploid rate on Day 5.