[Analysis of factors affecting live birth outcome of frozen-thawed embryo transfer cycle]

Objective: To analyze the related factors affecting the success of frozen-thawed embryo transfer (FET). Methods: A total of 563 couples treated in the Reproductive Medicine Center of Guangdong Hospital of Traditional Chinese Medicine from January 2017 to March 2020 were selected as subjects. A total of 736 FET cycles were included to analyze the live birth outcomes of FET. Pregnancy outcomes, pregnancy complications and embryo status of patients between the live birth group and the non-live birth group were compared. A multivariate logistic regression model was used to evaluate the association between the 15 candidate factors and live birth outcomes for identifying independent factors associated with the live birth outcomes of the FET. Results: Among the enrolled subjects, the men were (33±5) years old at sperm extraction while the women were (31±4) years old at ovum pick-up (OPU) and (32±4) years old at embryo transfer (ET) and their infertility duration were (3.5±2.6) years. There were 333 (45.2%) live birth cycles and 403 (54.8%) non-live birth cycles in the 736 FET cycles. Pregnancy complications occurred in 49 cases (14.7%) of the live birth group. The age of the women at ET ((31±4) vs (32±4) years), the age of the women at OPU ((30±4) vs (32±4) years) and the age of the men at sperm extraction ((33±4) vs (34±5) years) in the live birth group were all lower than those in the non-live birth group. The infertility duration was shorter ((3.2±2.2) vs (3.6±2.8) years), and the proportion of primary infertility was higher ((63.1%, 210 cases) vs (49.6%, 200 cases)) in the live birth group (P<0.05) than those in the non-live birth group. Multivariate logistic regression analyses showed that the age of woman at ET (OR (95%CI): 0.50 (0.27-0.92), P=0.026), the types of infertility (0.62 (0.43-0.88), P=0.008), the numbers of optimal embryos transferred (1.60(1.11-2.31), P=0.012), and the types of embryos transferred (2.43 (1.46-4.01), P=0.001) were statistically significant related factors for live birth outcome of FET. Conclusion: The age of the woman at ET, the types of infertility, the numbers of optimal embryos transferred and the types of embryos transferred are associated factors for the outcomes of live birth after FET.