A Systematic Review Of Clinical Efficacy Of Frozen-thawed Embryo Transfer In In-vitro Fertilization Cycles

Objective:To systematically evaluate the clinical effects of frozen-thawed embryo transfer and fresh embryo transfer in the in-vitro fertilization cycles,for improving the clinical outcomes of the patients.Methods:The computer retrieval of Medline.Cochrane Library,Ovid,EMbase,PubMed,ISI Web of Knowledge,CBM,Wanfang databases and the manual retrieval of relevant journals of gynaecology and obstetrics in China were performed.Literatures concerning randomized controlled trials in relation to the comparison of the clinical efficacy between frozen-thawed embryo transfer and fresh embryo transfer in the in-vitro fertilization cycles were searched.Moreover,there were two researchers responsible for the independent extraction of data and for the evaluation of methodological quality.Evaluation indexes included clinical pregnancy rate,on-going pregnancy rate,miscarriage rate and ectopic pregnancy rate.Then the meta-analysis was conducted by using RevMan 5.2 software.Results:A total of six randomized controlled trials and clinical controlled trials were included,involving 28803 patients.The results of the meta-analysis were shown as follows:Compared with the fresh embryo transfer,the frozen-thawed embryo transfer was superior in the clinical pregnancy rate[OR=1.12, 95%CI(1.07,1.18),P<0.00001],on-going pregnancy rate[OR=1.65,95%CI(1.19,2.29), P=0.003] and ectopic pregnancy rate[OR=0.51,95%CI(0.41,0.62),P<0.00001].However, there was no statistical differences in the miscarriage rate[OR=1.39,95%CI(0.95,2.03), P=0.09].Conclusions:These findings indicate that in the in-vitro fertilization cycles the frozen-thawed embryo transfer is better than the fresh embryo transfer in improving the clinical pregnancy rate,on-going pregnancy rate and decreasing the ectopic pregnancy rate. Therefore,this study provides the clinicians with a feasible alternative.Due to limited quality of the included studies,the aforementioned conclusion needs to be verified by conducting more high quality studies and more centers.