The safety of long-term cryopreservation on slow-frozen early cleavage human embryos
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To evaluate the impact of cryopreservation storage time on cleavage-stage embryo survival rate, pregnancy rate, implantation rate, singleton birth weight, and live birth rate.
This study was a retrospective analysis, including 867 thaw cycles and 3,367 embryos. Women who underwent IVF-FET cycles between 2005 and 2012 were analyzed. The patients were divided into four groups, as follows: group 1 (12–23 months); group 2 (24–35 months); group 3 (36–48 months); and group 4 (≥48 months).
The storage time did not have a significant effect on survival, damage rate of the blastomeres, implantation rate, pregnancy rate, singleton birth weight, and live birth rate for embryos frozen at cleavage stages.
Storage time did not influence the survival and pregnancy outcomes of slow-frozen early cleavage human embryos. The developmental potential of cryopreserved human embryos with different storage times does not appear to have a negative influence on further development.
KeywordsEmbryo cryopreservation Cleavage stage Survival Singleton birth weight Live birth rate
The authors would like to thank Lixue Chen who is the senior statistician in our department for analyzing some data.
The authors would like to thank Natural Sciences Foundation of China (Grant Nos. 30900512 and 810705340/H0426) for supporting this work.
Conflict of interest
Conceived and designed the study: P.L., J.Q.; Collected data and wrote the paper: L.Q.L., Y.L.; Assisted to collected data: M.L., S.L.L.; Assisted to write the paper: J.H., X.L.R.
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