What Having a ‘Perfect’ Embryo Actually Means

Embryo grading. The most confusing, terrifying thing after egg retrieval. Patiently waiting for the phone call with the daily lab report update. How many fertilized? How many survived? And on the final day, what did we end up with? So many questions surround embryos, and we often ask what does this all mean?!

I’ve definitely been in the IVF game long enough that I’ve researched the basics, including what is considered a top embryo (4AA/5AA) and how many days do the labs allow them to grow (typically 3 or 5 days). But after having a recent transfer, I was curious about the complete breakdown of what it actually means to transfer a top quality embryo, the embryo that we all desperately strive for.

First, let me introduce a picture that shows each embryo (Number/Letter Grading):

embryo grades

Based on this chart, it’s clear which embryos are considered ‘poor’, ‘average’ and ‘good.’ Notice that this chart hasn’t included embryos with a day 5/6 grading. When a blastocyst scores a 5AA grade, it means its starting to “hatch” with normal appearing inner cell mass and trophectoderm. Therefore when a blastocyst scores a 6AA on day 5, the blastocyst is completely “hatched” with nice inner cell mass and trophectoderm.


What does it mean to transfer a top quality embryo then?

If you are considered the lucky few who got a 4AA or 5AA embryo, the pregnancy success rate is considered to be 63-65% for a single transfer. These embryos implant as well as PGS tested embryos (genetically tested). What surprised me the most about high quality embryos was actually the gender stats. Did you know that you have a 72% chance of a top quality embryo being a boy?! That means you only have a 28% chance for a girl. Boy embryos develop quicker in the early stages, which is why there’s such a drastic difference between the two. Gender selection is nearly impossible at this stage then. I personally managed to get a girl (4AA) and a boy (5AA), so anything is possible!

With all of this information, it’s not surprising that we all want an army of top quality embryos! There are many things you can do to try to increase egg and sperm quality. A lot of couples start with supplements and lifestyle changes at least 3 months before a fresh IVF cycle. There are a lot of resources out there, including books, that outline optimal fertility diets. Your Dr can also advise you on this!

XOX The IVF Warrior