The Impact of Cleavage and Blastocyst Stage Sequential Transfer on Clinical Pregnancy Outcomes of Frozen Embryo Transfer in Patients with Multiple Transplant Failures: A Retrospective Cohort Study

Chenyang Huang,1– 4,* Jingyu Liu,1– 4,* Xiaoyue Shen,1– 4 Jie Mei,1– 4 Yue Jiang,1– 4 Hui Zhang,1– 4 Na Kong1– 4 1Center for Reproductive Medicine and Obstetrics and Gynecology, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing, 210008, People’s Republic of China; 2Center for Reproductive Medicine and Obstetrics and Gynecology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People’s Republic of China; 3Center for Molecular Reproductive Medicine, Nanjing University, Nanjing, 210008, People’s Republic of China; 4State Key Laboratory of Reproductive Medicine and Offspring Health, Nanjing Medical University, Nanjing, 210008, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hui Zhang, Center for Reproductive Medicine and Obstetrics and Gynecology, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing, 210008, People’s Republic of China, Tel +8625-8310-6666-76208, Fax +8625-8310-7188, Email hellozhanghui@sina.cn Na Kong, Center for Reproductive Medicine and Obstetrics and Gynecology, Drum Tower Clinic Medical College of Nanjing Medical University, Nanjing, 210008, People’s Republic of China, Tel +8625-8310-6666-76208, Fax +8625-8310-7188, Email xtalkn@163.comBackground: To assess sequential embryo transfer’s impact on clinical outcomes in frozen embryo transfer (FET) cycles for patients with multiple transfer failures.Methods: This retrospective cohort study encompasses 4,499 FET cycles involving double embryo transfers conducted at the Reproductive Medicine Center of Nanjing Drum Tower Hospital from 2020 to 2023. Group analyses were performed based on the type of transferred embryos (cleavage-stage embryos, blastocysts, and sequential embryo transfers) to assess the correlation between sequential transfers and clinical pregnancy rates, live birth rates, and multiple pregnancy rates. Subgroup analysis focused on patients with > 3 prior failures. Multivariate logistic regression adjusted for confounders.Results: Sequential transfer did not improve clinical pregnancy (aOR = 0.94, 95% CI: 0.67– 1.32, p = 0.73) or live birth rates (aOR = 0.90, 95% CI: 0.65– 1.23, p = 0.49) versus blastocyst transfer, but significantly reduced multiple pregnancies (aOR = 0.50, 95% CI: 0.34– 0.75, p = 0.0008). Among patients with multiple failures, sequential transfer showed no significant association with clinical pregnancy (aOR = 0.57, 95% CI: 0.29– 1.11, p = 0.09) or live birth rates (aOR = 0.94, 95% CI: 0.49– 1.81, p = 0.85), yet significantly lowered multiple pregnancy odds (aOR = 0.30, 95% CI: 0.10– 0.90, p = 0.03).Conclusion: Sequential embryo transfer does not enhance clinical pregnancy or live birth rates in FET cycles, regardless of prior failure history, but effectively reduces multiple pregnancy rates. For patients with > 3 embryo transfer failures, it yields live birth rates comparable to blastocyst transfer, representing a potentially advantageous option for this population.Keywords: sequential embryo transfer, recurrent embryo transfer failure, frozen embryo transfer, live birth rate, multiple pregnancy rate