Day 7 blastocyst euploidy supports routine implementation for cycles using preimplantation genetic testing

Abstract

OBJECTIVE: To determine if Day 7 blastocysts merit biopsy, vitrification and transfer consideration by contrasting their aneuploidy and implantation rates to Day 5 and 6 blastocysts. METHODS: A total of 1,925 blastocysts were biopsied from 402 PGT-A cycles over a 12 to 16 month interval. All embryos were cultured under tri-gas, humidified conditions (37ºC) for up to 7 days (168 hours post-insemination). Biopsied blastocysts were vitrified and trophectoderm samples analyzed using NextGen sequencing. Single euploid embryo transfers were performed (n=254) using either a Day 5 (n=145), Day 6 (n=92) or a Day 7 blastocyst (n=16) post-warming. Euploidy rates and pregnancy outcomes were subsequently assessed and differences determined by day of development and blastocyst quality grade. RESULTS: <0.05) live birth rates (43.8% vs. 67.4-77.2%). CONCLUSION: Culturing blastocysts to Day 7 has proven beneficial by achieving viable euploid embryos that would have otherwise been discarded. An extra Day of embryo growth allows select patients additional opportunities for in vitro development and possible healthy term live births.