When it comes to IVF, there is a lot of emphasis placed on the quality of the embryos. Because doctors and patients want to have the best chance possible for success during an embryo transfer, clinics attempt to choose the “best” embryos of the bunch. To do this, an embryologist examines the embryos during the first 3-5 days of their growth and gives them a grade. Grading scales can vary, but they are typically an A-B-C grade or on a scale of 1-5, with 1 typically being the best.
To determine the grade, an embryologist will look at factors such as:
- How much fragmentation is left behind from cell division (while fragmentation isn’t well understood, most doctors will agree that fragmented embryos have less chance of becoming a healthy baby).
- The size of the cells and how they compare to each other. Cells that are roughly equal in size to each other are given a better grade.
- Other aspects such as the thickness of the shell of the embryo, the presence of vacuoles (bubbles that supply nutrition to the cell), etc.
Cells that are given the best grade are likely to be transferred first. Because of this, some people who are considering embryo adoption wonder if they are getting leftover embryos that aren’t rated as highly. In some cases that could be true; couples using IVF are going to use their highest-rated embryos first to increase their chances of success. However, it may not matter.
Embryo grading is incredibly subjective and ultimately left up to the discretion of the embryologist doing the examination. What one fertility clinic rates as a B+ another clinic may give an A. In both IVF and embryo adoption, happy, healthy babies have been born from embryos given lower grades and even from embryos that were thought not to be viable candidates at all. Ultimately, all embryos are created to give them a chance at life and their grades may not matter, especially when you are holding a baby of your own in your arms. You can learn more about embryo grading and adopting frozen embryos at EmbryoAdoption.org.