Endometrium
Also written as womb lining
The lining of the uterus, which thickens across the menstrual cycle and is where an embryo implants.
In plain English
It's the lining inside your womb that thickens up and is where the embryo needs to embed for a pregnancy to start.
Why it matters
Clinics measure its thickness on scans to help judge the best timing for embryo transfer.
Related terms
Guides that cover this
Written by patients, not clinicians. This page has not yet been reviewed by a named fertility professional, so it explains published guidance and points you to the original source instead of giving medical advice. It is not medical advice. Decisions about your treatment belong with your own clinic. Read our editorial policy and corrections policy.