Trophectoderm grade predicts outcomes of single blastocyst transfers

Trophectoderm grading, but not inner cell mass grading, significantly correlates with implantation and live birth for single-embryo transfers.

Micah J. Hill, D.O., Kevin S. Richter, Ph.D., Ryan J. Heitmann, D.O., James R. Graham, M.S., Michael J. Tucker, Ph.D., Alan H. DeCherney, M.D., Paulette E. Browne, M.D., Eric D. Levens, M.D.

Volume 99, Issue 5, Pages 1283-1289.e1, April 2013


To estimate the effect of the embryo stage, trophectoderm (TE) morphology grade, and inner cell mass (ICM) morphology grade on live birth in single blastocyst transfers.

Retrospective cohort study.

Large private ART practice.

Fresh autologous ART cycles.


Main outcome measures:
Live birth.

A total of 694 single blastocyst transfers met inclusion criteria. Univariate regression analysis showed embryo stage and TE score to be correlated with implantation and live birth. Live birth rates were 57%, 40%, and 25% for TE grades A, B, and C respectively. There was no significant association with ICM grade and implantation or live birth. Live birth rates were 53%, 52%, and 0% for ICM grades A, B, and C respectively. Multiple logistic regression analysis showed that only patient age and TE grade were significantly associated with implantation and live birth, while ICM grade was not significantly associated with outcome. The TE score had the strongest correlation with live birth.

TE grading, but not ICM grading, significantly correlated with implantation and live birth for single blastocyst transfers.

  • Fernando Bronet, PhD

    These results are very interesting; we can see in the last years that other authors can find the same relationship in their study. In fact, we have showed our results in the last IVI Congress, were we found that in good quality blastocysts, trophectoderm was statistically related to the implantation rate regardless of the quality of the inner mass cell. It seems that trophectoderm morphology could be a better predictor for implantation rate.
    In other hand, De Paepe et al (Hum Reprod, 2013) found that isolated trophectoderm cells from full human blastocyst are able to develop into blastocyst with Inner cell mass.
    We must take into account trophectoderm more than now.

    • Micah Hill

      Thank you Dr Bronet for you insightful comments. I was unaware of the De Paepe paper and found it a very interesting read!

  • Ki

    Micah, this is a very valuable study. Few programs have enough single embryo transfer data to put together such a nice dataset. In regards to the correlations between ICM and TE grades with implantation and live birth rates, an additional possible conclusion is the need for improvements in meaningful embryo grading strategies. With nearly 90% of ICMs in the study receiving the top grade, there is a clear need for refinements. Whether those refinements will improve the predictive power of embryo morphology remains to be seen. Have you considered any alternative grading strategies based on these results?

    • Micah Hill

      Thank you for your comments Ki. I’m looking into your question and will get back with you. I agree with you that an additional conclusion to our results is the need for improvement in meaningful embryo grading strategies!

  • Micah Hill

    We appreciate the opportunity to report our study demonstrating that in a retrospective cohort of single blastocyst transfers, trophectoderm grading had the strongest correlation with live birth of any of the morphologic parameters. This is consistent with a publication by Ahlstrom et al. in Human Reproduction just over a year ago also evaluating single blastocyst transfers. These findings have potential implications to clinical embryo selection and single embryo transfer algorithms. We welcome any questions, comments, or discussion.

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