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The Effects of Different Post-thawed Culture Periods on Clinical Outcomes in Frozen Embryo Transfer Cycle


The purpose of this study is to evaluate the effects of different post-thawed culture periods on the clinical outcomes. 9381 frozen embryo transfer (FET) cycles were divided into three groups according to female age: < 35, 35–39, and > 39 years, and two groups depending on post-thawed culture period before transfer: short culture (2–3 h) group (S) and long culture (18–20 h) group (L). According to the increment number of post-thawed embryos, the L group divided into three groups: ≤ 2, one ≤ 2 and the other > 2, and > 2 groups. Pregnancy outcomes included the implantation rate (IR), clinical pregnancy rate (CPR), multiple pregnancy rate (MPR), live birth rate (LBR), and neonatal characteristics. Long post-thawed culture caused a significant increase in the IR, CPR, MPR, and LBR (p = 0.000, 0.004, 0.037, and 0.001; CI = 1.06–1.194, 1.042–1.237, 1.008–1.254, and 1.054–1.245, respectively), and blastomere increment number also had a significant effect on IR, CPR, MPR, and LBR (p = 0.000, 0.000, 0.000, and 0.000, respectively). No significant differences were present in neonatal characteristics between the two post-thawed culture groups. Singleton group had a higher average gestational age and birthweight as well as a lower cesarean section rate, preterm labor rate, and low birthweight rate than twins group. Long post-thawed culture was associated with higher IR, CPR, MPR, and LBR, and transferring a well-developed embryo after long post-thawed culture might be a viable embryo transfer strategy to decrease MPR while maintaining CPR and LBR.

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The authors would like to thank all participants and staff at IVF Center, Mali Hospital, Haikou, China and the Hospital of Shenzhen Immigration Inspection, Shenzhen, China.

Author information




The study was designed by YHL, BM, and LGZ. XXC, NL, and YHL were involved in planning and managing the data collection. YHL and BM were involved in the statistical analysis and wrote the manuscript with support and critical review from all authors.

Corresponding authors

Correspondence to Yuhu Li or Bo Ma.

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Ethical approval was granted by the Ethics Committee of Mali Hospital on March 8, 2020 (NO. 01/MH/2020).

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The authors declare no competing interests.

Additional information

Yuhu Li and Xuexiang Cai are co-first authors.

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Li, Y., Cai, X., Li, N. et al. The Effects of Different Post-thawed Culture Periods on Clinical Outcomes in Frozen Embryo Transfer Cycle. Reprod. Sci. (2021).

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  • Post-thawed culture period
  • Blastomere increment number
  • Neonatal characteristics
  • Live birth rate