Effect of blastomere cell number on ART outcome of fresh single day 3 embryo transfer.

Purpose: Explore the effect of blastomere cell number on ART outcome of fresh embryo transfer on day 3.

Methods: Retrospective analysis of 540 fresh single day 3 embryo transfer cycles at the Reproductive Center of the Third Affiliated Hospital of Guangzhou Medical University from January 1, 2018 to October 31, 2022. Patients were divided into 5-6 cell group (n = 55), 7-9 cell group (n = 457), and ≥ 10 cell group(n = 28) based on the number of blastomeres. Single factor analysis of variance and Pearson's chi square test were used to compare the basic data, cycle information, pregnancy outcome and neonatal outcome. Univariate logistic regression was used to correct for confounding factors and analyze the influencing factors of pregnancy outcome.

Results: The positive HCG rate were 20%, 43%, 25% for the 5-6-cell, 7-9 cell and ≥ 10 cell groups respectively, with statistically significant differences (P < 0.001). The clinical pregnancy rate was 18%, 42%,21%, respectively (P < 0.001). The live birth rates were 13%, 34%,21% with P-value less than 0.05 which is statistically significant. In order to exclude the influence of confounding factors, multivariable logistic regression analysis was performed, and the outcomes were consistent with previous findings. There were no significant differences found in neonatal outcome between groups (P > 0.05).

Conclusion: The results suggested that intermediate cleaving embryos (7-9 cell) still presents the highest clinical potential. Fast and slow cleaving embryos are not conducive to the ART outcome.