“If the scan date differs from your LMP dates, then the scan dates will be used, but do discuss with your midwife if you are concerned.
” Expert Jan Steward, who is director of Ultrasound Direct and Babybond, agrees that early scans carry a much greater risk of inaccuracy.
“At our clinics we scan from 7 weeks but at this time due dates are not totally accurate as it is very early stages.
These can be carried out from week 5 or 6 of pregnancy, which is a notoriously tricky time to be accurate on dates.
Understandably, when it is such early days it’s easy to worry when the scan dates are different to what you were expecting.
How did your baby's birth day line up with your predicted due date(s)? My other kids were born at 41w and 39w5d based on LMP (only had 20w ultrasound). We shall see :) So based on my LMP my due date was Jan 4, my first ultrasound Said Jan 4, my 20’week ultrasound said Dec 29, and my 36 week ultrasound had me measuring 39w3d! Sounds like the 20 week ultrasound was the closest!
Ultrasound (12w) said Jan 13th but I know when I ovulated so I am sticking with Jan 20th (plus I know my babies are big). Based on my LMP I'm due Jan 19th but 12w ultrasound said January 12th so the midwife has set my due date as Jan 15th!!
As Loobylou77 explains, it's really common for these to change when it comes to the dating scan at around 12 weeks.
“I was measured at 6 6 (6 weeks and 6 days) when I should have been 8 weeks.
Measurements at such an early stage aren't accurate which is why they wait for 12 weeks to date you.
"At my 12 week scan I was back to bang on dates for my last period and was told to ignore the previous two scans, which they said were to check for 'viability' as opposed to dates.
The healthcare professionals will stick to this date as far as possible because it is then used as the baseline for growth throughout pregnancy." While the professionals like to try and stick with the date that you’re given at your dating scan, it can and does change. "I'm 16 5 and have already been given 3 due dates and its changed for a 4th time back to the 2nd estimated due date! I have scans every few weeks so it will probably keep on changing.