Back to glossary

Fertility Glossary

Inner cell mass (ICM)

The cluster of cells inside a blastocyst that becomes the baby.

Embryology

The ICM is graded (often with a letter) as part of blastocyst grading, alongside the trophectoderm.

Also known as: ICM

Last reviewed: 23 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.

Explore in-depth guides

Learn more with Antega's fertility guides and articles.