Mum or mummy?

[recently]

We live abroad and ds14 still calls me mummy - probably because he hasn't heard anyone swap to mum. Should I suggest it? What age did your dc start using mum?

Why not let him call you what he’s comfortable with? Mine is six and has always called me by my first name — his idea, not mine — which some people are horrified by.

My dad called my grandmother mummy until the day she died. He was in his 50s.

My son has started letting mummy slip to mum on occasion. He's 9. He usually says mum in reference though "let me check with my mum" when talking to his friends but then says mummy when talking to me.

I think around about when they were starting school - so 4 yrs old

Why not let him call you what he’s comfortable with? He's fine with mummy but I think he might find it embarrassing when in the UK that most teenagers don't say mummy.