Comparison of Clinical Outcomes Between Fresh Embryo Transfers and Frozen-Thawed Embryo Transfers

Background: advances in embryo culture technology and cryopreservation have led to a shift in in vitro fertilization (ivf) from early fresh or frozen-thawed cleavage embryo transfer to fresh or frozen-thawed blastocyst stage transfer.objective: to compare the clinical outcomes of fresh embryo transfers and frozen-thawed embryo transfers.materials and methods: in this retrospective case control study, patients undergoing ivf cycles from january 2012 to december 2012 were enrolled in assisted reproduction of wuhan union hospital were enrolled. a total of 1891 cycle contains 1150 fresh embryo transfers and 741 frozen-thawed embryo transfers were studied. all data were transferred directly to spss 18 and analyzed.results: clinical pregnancy rates of fresh cleavage-stage embryo transfers compared with fresh blastocyst transfers, frozen-thawed cleavage-stage embryo transfers, post thaw cleavage-stage extended blastocyst culture transfers and frozen-thawed blastocyst transfers were 52.7%, 35.88%, 35.29%, 47.75%, 59.8% in patients under 35 years of ages and 41.24%, 26.92%, 11.32%, 46.15%, 55.8% in patients older than 35 years old, respectively. the multiple pregnancy rates, abortion rates and ectopic pregnancy rates did not differ significantly among the five groups.conclusion: the clinical pregnancy rates were not different significantly between fresh cleavage-stage embryo transfers and fresh blastocyst transfers. but the clinical pregnancy rate of frozen-thawed blastocyst transfer was the highest among fresh/frozen-thawed embryo transfers.