Dating scan 4 weeks out??!

[Donna8]

Hi there, on my 4th pregnancy and by my dates (and pretty positive on this) had lmp on 23 nov 10, and conceived on 28th nov 10. So this should make me just around 10 weeks going by conception date. Also been feeling like crap since Christmas and had a pos preg test on 28th dec, I was a week late at this stage. HOWEVER, went for a dating scan today and told I am only 6 weeks!!?!! I am amazed!! Don't understand this at all as always have regular periods and sure of dates! The sonographers did say they thought there was a heart beat which is a relief as been having slight bleeds ( brown or pink) for past 5 days on and off and sm worried about this. Has anyone had similar with scans? I feel like asking for a second opinion???
Many thanks ;)

I went for my dating scan today having had 2 previous scans.

I've known since doing my test on 21 Nov that my due date was 29 July. However, I went for a scan on Monday Dec 6 when I was told I was 5 weeks (technically not possible) then another scan on Dec 21 when I was told I was 7+4. Todays scan has put me at 13+3 which is exactly what I said I was all along!

I queried this with the sonographer today and she said that it's really difficult to date when it's so small as it's really crunched up!

So, I've been kind of ten days either way but I must admit I've never been 4 weeks out!

If they're saying you're only 6 weeks then are they offering you a proper 'dating' scan in 6 weeks' time when you'll be 12 weeks according to them? As buttonmoon says, it may be that they then revise the date to be what you said all along. I think they're about a week out with me, but 4 weeks is pretty mad!

When you say you conceived on 28th, do you mean you did the deed then? As sperm can live for 7 days afterwards (and possibly even longer), it's possible you only actually conceived about a week later. But that only accounts for a week...and early scans aren't particularly accurate for dating.

Congrats anyway!

Donna do you chart your cycle? Only it would seemthat ifyour period started on the 23rd of november, it would be very unusual to ovulate on the 28th (which would be day five of your cycle - the 'average' woman will ovulate on day 14, but many women will be a couple of days either side). Also, as you seemed to expect your period on the 21st December, it would seem your usual cycles are about 'average' which, again, would make ovulation on cycle day 5 very unusal. And I am saying 'ovulation' as if you're thinking that's when you conceived, well, you can't conceive without an egg (which lives for around 12-24 hours).

If you're meaning that 28th November is the only time you've had sex, then as bunny says, it may be a case of the sperm managing to live inside you for some time... but four weeks out would be pushing it. More likely is you actually ovulated later than 'average' which could account for many three weeks and then factor in... human error when measuring. Or, probably more accurately, a combination of these factors.

You probably need another scan around 12 weeks to properly 'date' the pregnancy.

Hi bunnyfrance, yes did the deed on the 28th so u r right would have conceived a week later. But as u say, only accounts for about a week! Spoke to midwife who is going to arrange another dating scan in 2 weeks time which I hope will be abit more in line with my dates. ;)