Successful pregnancy following replacement of embryos previously refrozen at blastocyst stage

We present the first reported clinical pregnancy following transfer of embryos that had been subjected to two freeze-thaw cycles: the first at day 3 after insemination, and the second after culturing to the blastocyst stage. A 25-year-old woman undergoing IVF treatment for male factor infertility opted for intracytoplasmic sperm injection (ICSI). ICSI treatment resulted in the successful production of 19 early cleavage embryos, all of which were frozen. After thawing, the embryos were cultured to the blastocyst stage. Thereafter, the blastocysts were refrozen and again thawed prior to embryo transfer. Embryos surviving a day 3 freeze-thaw cycle developed to the blastocyst stage and survived the second freeze-thaw cycle. Successful clinical pregnancy resulted following two sequential freeze-thaw cycles. This finding shows that it is possible to refreeze supernumerary blastocysts for subsequent transfer.