Lmp or scan date? Which is the one you use?

Scan should be more accurate and is what the midwives will use. But with 4 days difference and the likelihood of then coming on their due date being 5%, it really doesn't make much difference. Mine was calculated as 29th December by LMP and 2nd Jan if adjusted for my cycle length, but the NHS used 29th December until my scan came back as 4th Jan.

Always scan date. That measures the actual baby, not an estimate based in your period. But given there is only 4 days difference, i wouldn't worry!

I’d say scan date however it doesn’t matter too much as my daughter was due 20th November and came 29th November

everything will go on your scan date such as midwife appointments etc