Dating scan dates

[Mummymummyme]

I was wondering if anyone here could help me? My dating scan has put my due date back 12 days to 3rd Feb from my LMP date of 22nd Jan. Is the reason they pushed my dates back because I ovulated late? Are there any other reasons? How far out can dating scans be?

[DuggeeHugs]

As far as I know dating scans go by foetal size as they can't tell exactly when you ovulated or how long after ovulation fertilization occurred.

In terms of how far out, with my first DC the LMP gave 03 July as the due date. The scan gave 01 August. The scan was correct but I doubted a bit all the way through! I don't have a cycle though - 'normal' is anywhere between 10 days and 6 months. Was a bit surprised it is only a 3-day difference this time.

[Emma2803]

It depends on how far along you are but I would only expect them to be out by a few days. Between 10-14 weeks I believe you will get a pretty accurate date.
I had a scan when I was 9+6 but which dated baby as 9+3. I am positive about when I ovulated as I get very obvious ovulation pains and was doing ovulation tests . When I went back at 13+3 (going by my dates) baby was measuring exactly 13+3.

I would say 12 days out is a lot and unless you are certain of when you ovulated I would go with the scan dates.

[peachgreen]

I was 5 days behind at a scan at 6+4. By the time of my next scan I'd jumped to almost a week ahead! Trust the most recent scan date you've had but know that it can change.

[user1499085914]

With my second I never had a period as it was so soon to giving birth so I had a dating scan& they was spot on my little boy came dead on his due date, my birthday, was happy about not waiting long tho x