Which due date - by LMP or by dating scan?

[BarbieLovesKen]

Hi all,

Im certain of the day of my last period - August 25th which would, by my calculations, make my due date 1st June.

I paid for a private scan at 8weeks(ish) and Doctor said baby was measuring 6 days "ahead", making due date 28th May.

I then had dating scan with hospital at 17 weeks. Again, measurments = 6 days ahead and baby due 28th May however, consultant didnt make any reference to this (I read it off screen) or change my due date - actually when he asked my LMP, he worked it out that I was due 2nd June.

This is my 3rd dc and other 2 have been bang on dates. I know Im being silly - its only a few days (but as most pregnant women will relate, being almost a week ahead is a big deal ).

Does anyone have any experience? I've been going with 2nd June (although Im certain its 1st) as this is what the hospital are going with and I dont want to get fed up and annoyed when 28th May passes and Im "overdue" (when I wouldnt be really). That said, I've dates to finish up work prepared and exam dates for college all worked around a certain due date.

If I go my LMP the babys due on the 11th July but at my dating scan they said 7th July and to be honest I've stuck with the 7th July because it feels closer if only by 4 days!

I've had something similar with my current pregnancy.

I've got a discrepancy of 10 days between my LMP date and the date from the scan.

I know my ovulation/conception date and it backs up the date based on my LMP. There's just no way the scan date is correct. I've just got a baby that measured large.

I think the issue will be when you and I supposedly "go overdue" and then come under pressure to be induced.

I don't know the answer. Perhaps insist on another scan nearer your due date?

Its a pain, isnt it?. I dont know my ovulation date though so Im wondering if I am actually due 28th May. Your right - Im worrying that Ill think Im overdue when Im not even due yet, if that makes sense and Im expecting this one to be late anyway as I've had 2 "late" babies. (so definately expecting arrival after 1st June in which case I'd be really fed up if I think Im due 28th may).

I'd still (like you, jumping) love to be a whole week ahead

Thanks for your replies

With my DS I worked out to be due 6th dec 08 from LMP but at 12 week scan they said 2nd dec....so I went with the 2nd and that is when he was born!!
I am 8 weeks today with DC2 and due 26th October, 4 weeks till my scan and all going well I will go by the date they give me at the scan.........although I do not expect them to be as accurate!

I also don't trust my dating scan date i measured 9days over what I think my date is and like some people above I know the date of my last period and when I ovulated so really don't see how it can be over a week ahead. I'm tall so think its just a long baby! Again as already said only an issue if have to be induced or a planned section beforehand.

Babies are pretty much uniformly sized in the first trimester. They only become 'big' or 'small' for dates later. So if 2 early scans put you 6 days ahead, I'd say you're 6 days ahead of lmp. An lmp date only assumes you ovulate on day 14. If you didn't, then it won't be accurate.

And anyway, doesn't matter what they say, the baby will still come when it's ready, whether that's at 37 or 42 weeks or anything else really.

When i had my 12 week scan she told me i was 12+1

I was absolutely certain of dates and ovulation etc etc.
The scanner person told me that (at least at that stage of pregnancy) they are correct within + / - 5 days.

so i have decided that i AM right, though in my notes am due 2 days earlier... but thats within normal scan accuracy

Showy, what you're saying makes sense. But I know my ovulation date and it was day 11 (always is). So that explains a 3-day discrepancy.

Then allow +/-5 day window of accuracy.

But 10 days out....I don't understand that at all!

I am 6 days out apparently - but that is impossible.

OH was home at days 11-14 after LMP. Obviously, calendars assume I ovulated on day 14. Maybe I ovulated on day 10 which is unusual, but even then I could possibly only measure 4 days over.

Am glad I have an understanding OH!!

Hi

I had the same thing with my DS, off my LMP he was due on the 16th December, off the scan dates he was due 9th December. I just went with the 9th December as it was a week earlier and also less chance of a Christmas Day baby

By the 9th of December, I was throughly fed up and was expecting to be induced 10 days later as DS showed no signs of budging, then lo and behold it all kicked off on the 15th December and he was born later on that afternoon, so even though I say he was 6 days late - he was really a day early