Having a safe pregnancy and receiving a healthy child it’s what concerns women undergoing surrogacy services. Thanks to the ever-evolving process of constant medical improvements, it is possible for doctors not only to calculate the success rate of embryo transfer but also to evaluate each fertilized egg, making beneficial forecasting for a mother-to-be.

What does embryo rating mean and how it is done? Find out in the blog post below.

What Does 4AA Embryo Mean?

Before giving an answer to this question, let’s talk about embryo development stages to understand the whole picture. Firstly, the eggs are retrieved and then fertilized by sperm, forming a zygote. Going through a series of cell transformations, the zygote becomes a blastocyst within 5 days period of time after the retrieval.

So when we consider the 4AA embryo, this is a blastocyst that has been graded to predict what is the success rate and probability of the pregnancy. For instance, 4AA embryo grade is a good one, meaning that there’s a high chance of conceiving a healthy baby. But more about the embryo grading system you may find out in the next segment. 

Embryo Grading System: The Difference Between 4AA and 1CC embryos

A typical grade in the blastocyst grading system contains a number and 2 letters:

• The number indicates the level of blastocyst expansion and its overall development from 1 to 6 (where 5 is the best score);
• The first letter describes the quality of Inner Cell Mass (ICM) of the future implanted embryo (A-C, A being the best grade);
• The second letter shows trophectoderm quality ― a kind of epithelium (layer of cells) on the outer edge of a blastocyst. The grading is also from A to C, A is the best score.

Given such criterium, we can come to a conclusion, that the most evolved embryo is 6AA, and the least productive is 1CC. Nevertheless, the appropriate blastocysts for embryo transfers are of 4-5th level and A-B letter grade.

What’s more interesting, from a gender perspective, there’s a significant shift toward male embryos (almost in 70 to 30 proportion), since male embryos are more fast-growing rather than female ones. So the chance to receive a boy is much higher than having a girl when using graded blastocysts in the IVF cycle.

4AA Embryo Success Rate

Different embryo grades and transfer scenarios have not only scientific significance. The distinction in the blastocyst quality scores has a direct connection with the success of the future pregnancy. For instance, “perfect” embryo graders like 4AA and 5AA can guarantee a pregnancy rate of 65%. The average ones decrease to the 50% mark. And finally, those embryos of poor quality won’t be considered for implementation procedure, since the success rate is only a bit more than 30%.

To sum it up, it’s important to understand that an excellent 4AA grade isn’t the only way to receive a healthy child. Successful pregnancies occurred with the help of blastocysts with other quality scores. That fact implies that each motherhood journey is unique. So if you’d like to start your own surrogacy path and experience IVF treatment ― please fill out the form below and our team will contact you shortly for more details.