Impact of Day-3 embryo cell number on pregnancy, obstetric and perinatal outcomes in frozen-thawed single blastocyst transfer cycles - Report - MDSpire

Impact of Day-3 embryo cell number on pregnancy, obstetric and perinatal outcomes in frozen-thawed single blastocyst transfer cycles

  • By

  • Feng Xiong

  • Caiyun Wan

  • Xiaoqi Peng

  • Qing Sun

  • Shiru Xu

  • Lianghui Diao

  • Peilin Chen

  • Huixian Zhong

  • Meilan Mo

  • Tao Zhang

  • June 22, 2026

  • 0 min

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Clinical Report: Influence of Day-3 Embryo Cell Count on Pregnancy Outcomes

Overview

This study evaluates the impact of Day-3 embryo cell number on pregnancy outcomes following frozen-thawed single blastocyst transfer. Findings indicate that embryos with ≤5 or 6 cells are associated with lower odds of live birth compared to those with 8 cells.

Background

The quality of embryos, particularly assessed by cell number on Day 3, is crucial in in vitro fertilization (IVF) as it influences implantation and pregnancy rates. Understanding the implications of Day-3 cell count on subsequent outcomes is important.

Data Highlights

Cell Count GroupAdjusted Odds Ratio (aOR)95% Confidence Interval (CI)
≤5 cells0.690.56–0.85
6 cells0.760.60–0.95

Key Findings

  • Blastocysts from Day-3 embryos with ≤5 or 6 cells had significantly lower odds of live birth compared to the 8-cell group.
  • Adjusted odds ratios for ≤5 cells and 6 cells were 0.69 and 0.76, respectively.
  • No significant differences in obstetric and perinatal outcomes were observed between ≤5 or 6-cell groups and the 8-cell group.
  • The adverse associations for ≤5 cells were consistent across various subgroups defined by blastocyst quality.

Clinical Implications

Consideration of Day-3 embryo cell count may be important when selecting embryos for transfer, as lower cell counts are associated with reduced pregnancy outcomes.

Conclusion

The study highlights the significance of Day-3 embryo cell number in predicting pregnancy outcomes after frozen-thawed single blastocyst transfer.

Related Resources & Content

  1. Frontiers in Endocrinology, 2026 -- Impact of Day-3 embryo cell number on pregnancy outcomes
  2. Frontiers in Endocrinology — Outcomes of Day 4 Versus Day 5 Embryo Transfers Based on Fertilization Techniques: A Comparative Study
  3. The Journal of Clinical Endocrinology & Metabolism — Outcomes of Perinatal and Maternal Health Following Transfer of Blastocysts from Nonpronuclear and Monopronuclear Embryos
  4. Frontiers in Endocrinology — The predictive value of fresh embryo transfer pregnancy results on frozen embryo transfer outcomes: a cohort study
  5. Frontiers in Endocrinology — Outcomes of frozen embryo transfers from a large monocentric cohort (2982 cycles): towards a preferential use of cycles with a corpus luteum for endometrial preparation
  6. Guidance on the limits to the number of embryos to transfer: a committee opinion (2021) | ASRM
  7. https://doi.org/10.1093/humrep/deae010
  8. Frontiers | Impact of Day-3 embryo cell number on pregnancy, obstetric and perinatal outcomes in frozen-thawed single blastocyst transfer cycles
  9. Frontiers | Impact of rapidly cleaving embryos on blastocyst formation and single-blastocyst transfer outcomes
  10. Effect of day 3 cell number on the pregnancy and neonatal outcomes of vitrified-warmed single blastocyst transfer | European Journal of Medical Research | Full Text
  11. | www.nature.com/scientificreports --- | ---OPEN
  12. Day 3 embryo quality impact on euploidy rate and pregnancy outcomes: a retrospective study of 12,669 PGT-A embryos - ScienceDirect

Original Source(s)

Impact of Day-3 embryo cell number on pregnancy, obstetric and perinatal outcomes in frozen-thawed single blastocyst transfer cycles

  • by Feng Xiong, Caiyun Wan, Xiaoqi Peng, Qing Sun, Shiru Xu, Lianghui Diao, Peilin Chen, Huixian Zhong, Meilan Mo, Tao Zhang

  • June 22, 2026

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