Accuracy of dating from scans?

[Clydesdaleclopper]

Does anyone know anything about the accuracy of dating from ultrasound. My due date was brought forward by a week after my 12 week scan but I know that can't be right as I know the date that I ovulated (also the baby was moving about so much they gave up trying to measure him). The MW refuses to change the date but I don't want them to be regarding me as a week overdue when I'm not, particularly as I'm trying to get a home birth. Is there any info out there that I can use to persuade them to change my EDD?

I am in the same postition as you, I was due on Christmas Day, and after my 12 week scan, the hospital seem to be going by 19th December, they booked my 20 week scan for what was 19 weeks, so I am now going by the scan date. I am being seen by a consultant (due to previous pre eclampsia) but otherwise, midwives don't seem to change the dates. Quite glad the hospital seem to be going by the new date as Christmas would be a real pain! Anyway, my point is...midwives seem to go by your dates and not by the scan, so good luck!

I feel for you as I am the same, I don't want to be considered overdue when I know I am not. I have been put a whole week ahead of what I should be despite the fact that I had this baby through IVF and there is No confusion about when I 'ovulated'.

I am planning on talking to the midwife about it today and asking if I can please have my date moved to the correct date at the 20 week scan.

I will be refusing induction if they try it!

No idea what you can do to change anyones mind but I personally think they are terribly inaccurate!

With my DD I was given MANY different EDD's ranging from 30/11 to 22/12 . . She was eventually born on 01/01!

Everytime I had a scan they gave me a new EDD

At 12 weeks, even if they take perfect measurements, you're looking at +/- 1 week. IIRC latest research indicates that babies only develop at a constant rate for the first 8 weeks and after that there is a range of growth curves.

Ovulation date doesn't give you a cast iron EDD as not all babies will implant at the same time, but its another piece of the story. If your baby was moving around that much I'd be arguing as well. What did the sonographer write down?

Its also worth remembering that they're your notes, not the hospitals, and you can write what you like on them - they may have changed your dates, but you're perfectly at liberty to add a comment that you don't agree and consider your original date to be correct. {And that its not up to your MW to allow you a HB or otherwise - they can advise but only you can decide, be that at 12 weeks, 36 weeks or 44 weeks (by whichever set of dates ).}

That said, I know its much easier to try and sort it out sooner rather than later. It could be worth asking AIMS if they know of any guidelines/policies on dating - I think round here there has to be a discrepancy of >7 days at 12 weeks before they'll change your EDD. If that's standard for most PCT's then it gives more strength to your argument to have your dates put back where they came from.

Good luck

Seems a common occurance, I was told by midwife and doctor that I am due on the 20th September, I also worked this date out as my due date going by my LMP. When I had my scan I was put back a week and told that I am due on the 27th. I don't know how the scan can be correct when I am 100% sure about my ovulation dates.