Comparison Of Clinical Outcome Of Vitrified-warmed Blastocyst Transfer Cycles And Fresh Blastocyst Transfer Cycles

Objective:To compare the clinical outcome of fresh versus vitrified-warmed blastocysttransfer(BT) cycles.Design:Retrospective study.Setting:Medical university affiliated hospital.Patient(s):Women aged less than40years undergoing BT cycles.Intervention(s):Vitrification and warming of blastocyst with the Cryotop system.Main Outcome Measure(s):Clinical pregnancy rate(CPR),implantationrate(IR),and multiple pregnancy rate(MPR).Result(s):In110fresh BT cycle sversus136vitrified-warmed BT cycle sperformed fromJanuary2007to March2010,the IR and CPR of vitrified-warmed BT cycles were37.0%and55.1%, respectively, which were statistically significantlyhigher than the corresponding values of25.2%and36.4%obtained for fresh BTcycles.Additionally,the MPR was not statistically significantly different betweenvitrified-warmed and fresh BT cycles when a similar number of blastocysts wastransferred to patients.Conclusion(s):Vitrified-warmed BT cycles resulted in statistically significantly higher CPR andIR compared with fresh BT cycles.A new embryo transfer strategy is thereforeproposed whereby fresh BT would be avoided in the initial ovarian stimulationcycle.Instead,all the patient’s available blastocysts would be vitrified-warmed antransferred in subsequent cycles.