Abstract: Objective: To investigate the effects of two methods of endometrial preparation plans(hormone replacement after down regulationand hormone replacement) on the pregnancy outcome of frozen-thawed embryo transfer(FET) cycle in the advanced age infertile patients, and to analyze the influencing factors of pregnancy outcome of FET cycle of hormone replacement after down-regulation and to provide the basis for the selection of endometrial preparation scheme for FET cycle in the aged infertile patients. Methods: A total of 211 patients aged ≥ 35 years who first received FET treatment were selected.The patients were divided into hormone replacement cycle after down-regulation group(n=114) and hormone replacement cycle group(n=97).The age, duration of infertility, body mass index (BMI), anti-Mullerian hormone(AMH) level, basic sex hormones, endometrial thickness on the day of conversion, number of embryos transferred, number of high-quality embryos transferred, rates of high-quality embryos transferred,rates of multiple pregnancies, and abortion rates of the patients in two groups were analyzed, retrospectively, and the influencing factors of pregnancy outcome of hormone replacement cycle after down-regulating were analyzed by Binomial Logistic regression. Results: There were no significant differences in age, duration of infertility,BMI, AMH levels, number of embryos transferred, number of high-quality embryos transferred, rates of high-quality embryos transferred, rates of multiple pregnancies, and cycle abortion rates of the patients between two groups(P>0.05).The clinical pregnancy rate and embryo implantation rate of the patients in hormone replacement cycle after down-regulating group were significantly higher than those in hormene replacement cycle group(χ²=9.964,P<0.05;χ²=9.964,P<0.05). The results of Logistic regression analysis showed that age (OR=0.805,95%CI:0.697-0.930) and the number of high-quality embryos transferred (OR=4.098,95%CI:1.597-10.514) were the key factors influencing the pregnancy outcome of hormone replacement cycle after down-regulation in the advanced age infertile patients. Conclusion: Hormone replacement cycle after down-regulation can achieve the better clinical outcomes in FET in the advanced age infertility patients. Age and number of high-quality embryos transferred are the key factors affecting the pregnancy outcome of hormone replacement cycle after down-regulation in the advance age infertile patients.

Key words: advanced age, infertility, hormone replacement after down regulation, frozen-thawed embryo transfer, pregnancy rate