Transfer of blastocysts derived from frozen-thawed cleavage stage embryos improved ongoing pregnancy
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The aim of our study was to compare the transfer of embryos that are cryopreserved in cleavage stage after thawing with the transfer of embryos after thawing and culture in sequential media until blastocyst formation.
In this prospective clinical study, we have evaluated 134 cycles of ART treatment for infertility. Frozen embryos were thawed and then cultured in sequential media until blastocyst stage in blastocyst group and were compared with thawed embryos in cleavage stage group.
Implantation rate was significantly higher in blastocyst group (30 %) compared to cleavage group (17 %). No statistical differences were reported in chemical and clinical pregnancy rates between groups. Ongoing pregnancy rate was significantly higher in blastocyst group compared to cleavage group (42.9 vs. 24.6 %).
Our results indicated that blastocyst formation after thawing of cleavage stage embryos is a good predictor for embryo viability and pregnancy outcome.