Abstract: ABSTRACT Object:To investigate the effects of age and the number of embryo transferred on pregnancy outcomes in infertile patients undergoing FET.Methods:A retropective analysis was performed in our center on the clinical data of 1052 thawing cases from Jan. 2004 to December 2008 .Results:The implantation rate was significantly lower in A group compared with those of B group(P＜0.05), but higher than that C group (P <0.05). The abortion rate was significantly lower in A group compared with those of B group(P＜0.05).There were significant differences in multiple pregnancy rate and fetal reduction rate between E group and F group. Ectopic pregnancy rate among groups were no difference (P> 0.05). Conclusion: Patients ≥40yrs implantation rate decreased significantly.The number of transferred embryos has nothing to do with ectopic pregnancy and abortion rate occurs. Transplantation 2 embryos is the reasonable choice and elective single embryo transfer(eSET) is a new choice .

Key words: FET, Multiple pregnancy, Fetal reduction, Ectopic pregnancy