Embryo grading

Blastocysts are usually graded by expansion (a number) plus the quality of the inner cell mass and trophectoderm (two letters), for example 4AA. Grading predicts the chance of implantation on average, but a lower-graded embryo can still result in a healthy baby, and grading says nothing definitive about chromosomes.

Also known as: blastocyst grading, embryo grade, 4AA

Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.