I think mine was 36mm at 21 weeks, they didn’t seem concerned with this although I’m not sure of the normal ranges x
They checked mine as have had a LLETZ, but just said it was acceptable. Didn’t give me the actual measurement.
Mine was 30 and they said the minimum they like is 25 if that helps x
I did have mine checked as I had LLETZ procedure once for pre cancerous cells removal. Unhelpfully I can’t remember what it measured, but they said it was fine and no further intervention needed. They will definitely tell you if there is a concern and talk to you about a cervical stitch.