A healthy baby was born last year after the transfer of three donated embryos that had been frozen and thawed twice after being stored in liquid nitrogen for a total of about 13.5 years. (PubMed.gov)
It may seem this baby was brought into the world against all odds, but a new study has found the pregnancy and live-birth rates after the transfer of twice-frozen embryos are comparable to those with once-frozen embryos. (Health24.com) These preliminary findings may mean more viable embryos may be available for donation to another family’s attempts at family building.
Dr. Juliette Koch of IVF Australia and Royal Hospital for Women, Randwick, New South Wales, Australia, compared the pregnancy and live birth rates of twice frozen embryo transfers with once-frozen embryo transfers generated through the same fresh IVF or intracytoplasmic sperm injection (ICSI) cycles among a test group of 44 women who had 40 once-frozen and 52-twice frozen transfers. The success rates were nearly identical. Of 43 transfers of once frozen blastocysts, 11 resulted in pregnancies and six in live births. The 52 blastocyst transfers of twice frozen embryos resulted in 13 pregnancies and seven live births. (Fertility and Sterility)
Miscarriage rates were also similar between once-frozen embryos (five miscarried) and twice-frozen (six miscarried). In both groups, no birth defects were identified. (Health24.com)
The twice frozen embryos had a slightly lower survival rate than the once thawed embryos. Of the twice-frozen embryos, 82% survived the transition from -192 C to room temperature compared to 89% of the once thawed embryos. (Health24.com)
"This preliminary data is reassuring for reproductive endocrinologists that embryos are not significantly harmed by freezing twice,” Dr. Koch stated, "It is important to continue to assess outcomes, including long-term outcomes of development." (Health24.com)
Further evidence of the potential to achieve pregnancy comes from a 2007 study appearing in Fertility and Sterility which shows women who use their own embryos will have, on average, a 32% chance of delivering to term, whereas women using adopted frozen embryos will have a 35% chance of delivering them to term. To find out more information on this study and the process of embryo donation and adoption visit EmbryoAdoption.org
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