Open AccessWisdom of Freezing All Valuable Embryos
Author(s) -
Atsushi Tanaka,
Motoi Nagayoshi,
Yasuho Yanagihara,
Izumi Tanaka,
Takako Akahoshi,
Megumi Araki,
Nao Urabe,
Akihiro Tanaka,
Tatsuya Sato
Publication year - 2021
Publication title -
fertility and reproduction
Language(s) - English
Resource type - Journals
eISSN - 2661-3182
pISSN - 2661-3174
DOI - 10.1142/s2661318221500201
Subject(s) - embryo , embryo transfer , embryo cryopreservation , cryopreservation , intracytoplasmic sperm injection , andrology , blastocyst , endometrium , gynecology , pregnancy rate , blastocyst transfer , biology , pregnancy , medicine , embryogenesis , in vitro fertilisation , obstetrics , genetics , microbiology and biotechnology
Background: It is controversial whether that “Freeze-only” strategy is superior to Fresh embryo transfer in ART patients with normal ovarian response. There are two reasons supporting a “Freeze-only” strategy. One is that frozen-thawed embryos are transferred to a more physiologically receptive endometrium. While fresh embryos are transferred to a badly affected one because of controlled-ovarian stimulations, which cause the discordant development of the endometrium, when thawed-frozen embryos are transferred in a subsequent cycle the endometrium is not affected by high estrogen levels. The other reason is the big difference in cryopreservation and stimulation techniques. Methods: We investigated the annual ART reports in Japan from 1992 to 2018, and our clinical outcomes of frozen-thawed embryo transfers and fresh embryo transfers from 2015 to 2019. This enabled the assessment of the survival rate of frozen blastocyst by Cryotop safety kit after thawing in four different clinics. We compared the outcomes of frozen embryo transfer (FroET) to fresh embryo transfer. Results: The proportion of birth in Japan in the study interval found that FroET was responsible for 86.7% of births, compared to 13.3% of births resulting from fresh embryo transfers after IVF or intracytoplasmic sperm injection (ICSI). Clinical outcome of FroET in our clinic was significantly higher than that of fresh embryo transfer regardless of maternal age and number of collected oocytes. Average survival rate of frozen blastocyst by Cryotop safety kit after thawing in four clinics was over 95%. Conclusions: We believe that “Freeze-only high-quality blastocysts” is superior to fresh embryo transfer in terms of clinical outcome, at least when compared to historical results.