Are dating scans always right?

[ebeson]

ive just been for a dating scan, i thought i was 11.4 days pg , but according to scan im 12.3 days. I know my last period was 7th sept and only bd once that month on the 21st, so im a bit confused that they said i was a week ahead.

No, they go on the size of an average baby, not your baby. Every baby's different. The midwives tend to go on your date unless there's a huge difference.

i thought that too, but the scanner said that all babies are the same at this stage.

I think the earlier you have the scan the more accurate it will be. I was told they do develop pretty much the same in the early stages and then other factors can affect them. Was told they were accurate to about 4/5 days or so.

Hmm. ds's dates were different too but I know when my ap was due.

If it's any help my due date was moved back after both my scans by a week each time. DS turned up officially 2 weeks early but almost on his original DD. He didn't look like an early baby and was nearly 8 lb so I've always thought the original date was right and the scans were rubbish!

I was told thye can be a few weeks out in either direction.
When I was pregnant with DD3, I was very sure of my dates, and could pinpoint the weekend of conception; the dating scan would have brought my due date forward 10 days. If we had gone with that I could have been under pressure to be induced, unnecessarily.

I thought I was 11.3 at my 12 wk dating scan and they said I was 12.5 or 12.6. Told their dates are likely to be right and mw has gone from their dates too. Just had 20 wk scan and their dates are still a week ahead of mine. Like you, i knew when I'd conceived but mw said time between conception and implantation can vary considerably and this can be what makes the difference. Still a bit sceptical as i wassure about my dates tho!

I had IVF for mine so know without any shadow of a doubt the day they were conceived.

At 12 weeks they were both measuring a week ahead. Ds was born a week earlier than his original due date. (I'm still pg with dc2)