About the Embryo “Grading” Process
As embryologists, one of the most common questions that we get from patients is “What do the grades of my embryos tell you about my chances of becoming pregnant?” The answer to this question is not a simple one. The objective of this article is to explain how we grade embryos and what those grades mean as far as an embryo’s potential for development.
All embryo grading systems are subjective and while we can make educated guesses about an embryo’s potential based on the experience of many embryologists grading millions of embryos, there are always embryos with poor grades that make pregnancies and perfect embryos that do not. Also, no matter the grading system, the embryo grades do not tell us what is going on inside the embryo genetically.
We use grading systems to determine which embryos to transfer and/or freeze. Our transfers occur either 3 days or 5 days after a retrieval. Because embryos are developmentally different on these days, we have different grading systems for day 3 (cleavage stage) embryos and day 5 (blastocyst stage) embryos.