worried about changed EDD

[carol1973]

I'm pretty worried about the results of an early scan I had recently. (I discovered I had miscarried at the 12 week scan with a previous pregnancy so feeling slightly neurotic this time round!) I went for an early scan when I was convinced I was 6+5 as I had abdominal pains. It all looked ok (fetal pole, heartbeat) except that it was sized at 5 weeks. The only explanation I can drag out of my midwife and the EPU department is I may have got my dates wrong - infuriating as I know I havn't. (lets just say if I did get pregant later that my dates it was the immaculate conception!) I didn't ovulate until day 16 so thats a couple of days I can shave off, and I know it takes a couple of days to get pregnant but I just can't understand why its 12 days out! Can anyone offer me any info? Thanks x

Didn't they tell you that scans that early are not very accurate for dating? (In my experience the scan at 12 weeks has been a week out both times too, btw.) But in the early scans the baby is so small that a tiny inaccuracy in measurement can mean quite a big difference in dates. It's relaly not something to worry about. I'm just surprised they didn't tell you that...

Thanks for the reply. No they didn't tell me that. If fact when I got my 12 wk scan date through, they had scheduled it based on the early scan date and not my LDP. When I rang the hospital to ask if it could be brought forward and to explain why I was worried they just kept saying sorry but we go off the last measurements. Getting info has been like getting blood out of a stone!

The measurements aren't very accurate at all that early, basically because the embryo is so tiny that 1mm difference on the scan (possibly due to how its lying, the scanning technology or natural user error) makes a big difference in dates.

I had a scan at 8+4 and it was 6 days out compared to the 12 week scan.

As long as your "12 week" scan is done by 13+6 on either dates, it shouldn't matter.

Carol I have just had a very similar experience - went for an early scan last week when I was convinced I was 6 weeks, to be told the sac was measuring 4 wks 5 days and it was just explained breezily as 'some ladies get their dates wrong' and 'it could be as much as 5 days out'. I'm pretty sure I didn't get my dates wrong as I chart temps and use OPKs etc, so really think I could only be out by a couple of days, rather than the 9 days suggested by the scan.

I have another scan a week tomorrow (no heartbeat on the first one, but they said just to early) and the wait is agonising. I have been really stressing about it and v worried that my bean stopped growing at 4 wks 5 days .

The midwives doing my scan were similarly unconcerned but hasn't stopped me doing my head in!

The posts here are quite reassuring though. I am also a bit reassured that since the scan my pregnancy symptoms have worsened - I feel sick as a dog! Happy to chat any time though, as the waiting is really hard, isn't it?

If you saw a heartbeat at the scan, that is very very good (and means risk of ealy mc goes down a lot). Normally, you don't see a heartbeat before about 6 weeks. At that stage, everything is so tiny so easy to get inaccuracies. As PP have said, dating at 12 weeks is much more accurate so probably they will revise your EDD then anyway. In the meantime, congratulations, and it's really good news to see a heartbeat at this stage.

Hi Carol1973, I had an early scan when I was about 7+2 they dated me at just under 6 weeks, which was a bit worrying for me - but like you they saw all they should see and a heartbeat was there too - at my dating scan (had at 11 weeks) I was measured 10+3, so the baby had caught up somewhat! - Early scans are not accurate in terms of dating the stuff is so tiny that a tiny bit out makes a huge difference. If they saw a heartbeat your risk of miscarriage drops by loads. Hang in there, I do know how worrying it is esp when you've miscarried before xxxx

I had an early scan at what should have been 6+4...and was told that I was either less than 4 weeks or it wasn't a viable pregnancy. (No hb seen and no fetal pole, just a yolk sac). I was 100% definate of my dates, or I'd had an immaculate conception, so I was sure I was going to MC again.

Went back for a scan when I should have been (by my dates) 8+6, they saw a hb and fetal ole but baby was only measuring 6+1. Again I was told I'd probably MC as baby wasn't growing properly.

I went for a 12 week scan, when (by my dates) I should have been 12+1. And baby measured 12+1!

I am now 33+2, baby is growing very well, no apparent signs of any problems caused by being slow growing to start with, baby moving around like billy-O, so IME having a baby that is very slow-growing to start with does not necessarily mean that you are going to MC.

Good luck!

Remember also that normal gestation is 38 weeks so the 40 weeks is actually the full gestation + 2 weeks. So say if you had sex on the 15th and conceived in the 16th, your date of conception according to the scan will be the 2nd. That's because before scans pregnancies were always measured from the date of the last period, which is generally two weeks earlier than ovulation. Despite the fact that we now have scans, this system is still used (don't know why) so the date you conceived won't actually be the date your pregnancy officially began according to the health profession.

I had this, had a scan when I thought I was 9+1, they measured me at 7+4, 11 days out, I was sure my dates were pretty close as I tested +ve on day 26 of my cycle. By my 12 week scan i was only out by 2 days so my baby had caught up alot. They based my dates on the 12wk scan, by my 20wk scan baby was measuring spot on with my dates. Hes still measuring fine and I'm 36 wks now! I think early scans can be very unreliable!