I don't know the answer Tanya - whether its our internal justification for getting to meet our baby's sooner or ....... I have had three private births and thus three OBs and none of them have ever been anxious to change my dates if anything they shrugged off any differences from scans - they always went from the original LMP/Conception based date and just used the scans to check that bubs was growing and fluid levels were appropriate. They always stressed how inaccurate they could be from a dating perspective. Thinking on it we did use a change in date from a scan once but that was because I was violently ill and it allowed us to justify having a c/section at the local hospital rather than having to be moved to a more distant facility - it made 2 days difference to the outcome though not weeks.