Abstract: Objective：To investigate the outcome and its influence factors of frozen embryo transfer (FET) cycles. Methods：A total of 483 FET cycles were retrospectively analyzed, in our Center from January to December in 2016. According to the pregnancy success or not, those cycles were divided into the pregnancy group (253 cycles) and the non-pregnancy group (230 cycles). The basic clinical data, pregnancy outcome and the influence factors between two groups were compared. Results：The mean age of the pregnancy group was significantly less than that of the non-pregnancy group, while the number of optimal embryo for FET in the pregnancy group was more (both P＜0.05). Logistic regression analysis showed that the influence factors of FET outcome included age (OR=0.715, 95%CI: 0.550-0.930, P=0.012), embryo quality (OR=1.780, 95%CI: 1.323-2.395, P=0.000) and type of embryo (OR=1.737, 95%CI: 1.076-2.805, P=0.024). Conclusions：Younger age, blastula transfer, optimal embryo transplantation were more conductive to the planting success rate and the clinical pregnancy rate of FET cycles.

Key words: Embryo transfer, Pregnancy outcome, Cleavage stage, ovum;, Blastula, Retrospective studies