Article ID: WMC001063 2046-1690 Refreezing Does Not Affect Their Survival Or Implantation

Abstract The thawing of frozen human zygotes and culture to the blastocyst stage often generates supernumerary blastocysts which can be refrozen. A total of 9 recipients of donated oocytes and 35 women originally at risk of ovarian hyperstimulation syndrome had such blastocysts thawed. There were respective survival rates of 72.0% and 66.7%, and on-going pregnancy rates of 23.5% and 18.8% after transfer, which did not differ from the general IVF population of women receiving thawed blastocysts generated from fresh zygotes. The refreezing of blastocysts from thawed zygotes can therefore be undertaken with confidence