Association Between Pregnancy Outcomes and the Time of Progesterone Exposure of D6 Single-Blastocyst Transfer in Frozen-Thawed Cycles: A Retrospective Cohort Study

Abstract

Dan Qi,1– 9 Xi Zhang,1– 8 Fangli Li,10 Shengrui Zhao,2– 8 Qiumin Wang,1– 8 Wen Liu,2– 8 Lei Yan,1– 8 Yanbo Du1– 8 1State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, People’s Republic of China; 2National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, People’s Republic of China; 3Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, People’s Republic of China; 4Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, People’s Republic of China; 5Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, People’s Republic of China; 6Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, People’s Republic of China; 7Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No. 2021RU001), Jinan, Shandong, People’s Republic of China; 8Medical Integration and Practice Center, Shandong University, Jinan, Shandong, People’s Republic of China; 9Weifang People’s Hospital, Weifang, Shandong, People’s Republic of China; 10Department of Gynecology and Obstetrics, Public Health Clinical Center Affiliated to Shandong University, Jinan, Shandong, People’s Republic of ChinaCorrespondence: Yanbo Du, Center for Reproductive Medicine, Shandong University, Jinan, 250012, Shandong, People’s Republic of China, Tel [phone], Email [email protected]: The objective of this study was to assess reproductive outcomes of D6 blastocysts transferred on day 6 in comparison to those transferred on day 7 of progesterone exposure in frozen-thawed embryo transfer cycles.Patients and Methods: This retrospective cohort study included 2029 D6 single blastocysts from the first frozen-thawed embryo transfer cycles of patients at the Hospital for Reproductive Medicine Affiliated to Shandong University from February 2017 to January 2020. Participants were divided into Group A (blastocyst transferred on the 6th day of progesterone exposure, n=1634) and Group B (blastocyst transferred on the 7th day of progesterone exposure, n=395).Results: The live birth rate was comparable between Group A and Group B (38.7% versus 38.7%, P=0.999). Subgroup analysis revealed a significantly higher preterm birth rate in D6 single blastocysts transferred on the 7th day than in those transferred on the 6th day of progesterone exposure for natural cycle frozen-thawed embryo transfer (5.2% versus 11.3%, P=0.020). After adjustment for potential confounders, the differences in the preterm birth rate in natural cycles persisted (adjusted odds ratio 2.347, 95% confidence interval 1.129– 4.877, P=0.022).Conclusion: In frozen-thawed embryo transfer cycles, transferring on the 6th or 7th day of progesterone exposure of D6 blastocysts did not affect the live birth rate; however, when a natural cycle protocol is adopted, the possible preterm risk of transferring D6 blastocysts on the 7th day of progesterone exposure should be noted.Keywords: frozen-thawed embryo transfer, blastocyst transfer, endometrium preparation, live birth rate

Keywords

• frozen-thawed embryo transfer
• blastocyst transfer
• endometrium preparation
• live birth rate