Objective: 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.
Methods: 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).
Results: 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.
Conclusion: 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.