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Evaluation of the Connection Between Static Morphology on Pregnancy Outcome After Single Blastocyst Transfer

A.F. Bartolucci, C.A. Benadiva, J.C. Nulsen, L. Engmann

August 16, 2017
Emma Holt

Defining Key Terms

What is Single Blastocyst Transfer and Cleavage Stage Morphology? 

Before we dive into this retrospective study, let’s take a look at and break down what single blastocyst transfer (SBT) exactly is. First of all, a blastocyst is an embryo that’s 5-7 days old. Recently, day 3 embryos have been transferred into the womb during IVF treatments, and it is believed that transferring these better developed embryos or those that have reached the blastocyst stage make pregnancy more likely. On the other hand, cleavage is the division of cells in the early embryo. See the connection now?

These key terms are important to identify because in this article, we’ll be looking at whether or not the cleavage stage morphology from Day 2 and Day 3 is predictive of pregnancy outcome after transfer at the blastocyst stage.

In this article, you’ll learn:

  • The goal of this study and why it’s important
  • Who participated in the study and when 
  • Connections to ongoing pregnancies and deliveries 
  • Which Days are or aren’t predictive pregnancy outcomes 

Goal of the Study

What are the researchers trying to determine? 

There are strong correlations between cleavage stage morphology parameters and live birth outcome after cleavage stage transfer, but the significance of cleavage stage morphology on outcomes after blastocyst transfer is unclear. Researchers A.F. Bartolucci, MS, C.A. Benadiva, MD, J.C. Nulsen, MD, and L. Engmann, MD from the Center for Advanced Reproductive ServicesUniversity of Connecticut, Farmington, Connecticut, have set out to answer if one can predict pregnancy in the cleavage stage of morphology after transfer at the blastocyst stage. Data from this study may support the ending of static cleavage stage morphology assessment with uninterrupted culture to the blastocyst stage. I guess we’ll find out…

Methods & Data Gathered

Variables that determine correlations with ongoing pregnancies 

From January 2010 to September 2016, data from 8,352 cycles from 52 IVF clinics were reviewed in patients between 18-40 years of age having a single blastocyst transfer. Patients using donor oocytes, thawed oocytes, surgically retrieved sperm, and preimplantation genetic testing were excluded from this study. The Society for Assisted Reproductive Technology (SART) (SART) grading criteria was used for categorizing and comparing morphology parameters from Day 2, Day 3, and Day 5 of embryo culture. A “one variant” comparison was performed initially in order to identify variables that associated with ongoing pregnancy and delivery. A multivariate analysis of the morphology parameters was performed afterwards to determine if there was an independent association with ongoing pregnancy and delivery, too.

Results & Conclusion

What are predictive pregnancy outcomes and what aren’t? 

The univariate analysis showed age, number, AMH, BMI, and embryos frozen were considerably connected with outcome. The cell number on Day 3 correlated with outcome after univariate analysis but was not remarkable after controlling for these variables and blastocysts morphology. 

Overall, after transfer at the blastocyst stage, Day 2 and 3 static morphology parameters are not predictive pregnancy outcomes. The researchers found that a lack of significant interactions of Day 2 and Day 3 variables indicates that Day 5 contributions account for these findings. Hence, eliminating Day 2 and Day 3 morphology assessments will most likely NOT affect pregnancy outcomes after transfer at the blastocyst stage.


Is cleavage stage morphology necessary for selecting blastocysts for transfer?

Fertility and Sterility, September 2017, Volume 108, Issue 3, Supplement, Page e353


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