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. 2024 Jun 10:16:1067-1077.
doi: 10.2147/IJWH.S456706. eCollection 2024.

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

Dan Qi  1   2   3   4   5   6   7   8   9 , Xi Zhang  1   2   3   4   5   6   7   8 , Fangli Li  10 , Shengrui Zhao  2   3   4   5   6   7   8 , Qiumin Wang  1   2   3   4   5   6   7   8 , Wen Liu  2   3   4   5   6   7   8 , Lei Yan  1   2   3   4   5   6   7   8 , Yanbo Du  1   2   3   4   5   6   7   8
Affiliations

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

Dan Qi et al. Int J Womens Health. .

Abstract

Purpose: 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: blastocyst transfer; endometrium preparation; frozen-thawed embryo transfer; live birth rate.

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Conflict of interest statement

The authors report no conflicts of interest in this work.

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FET protocols.
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