Advanced search

Pregnant? See how your baby develops, your body changes, and what you can expect during each week of your pregnancy with the Mumsnet Pregnancy Calendar.

Did you trust your dating scan?

(16 Posts)
VanillaIce Fri 23-Oct-09 15:55:43

My 12 week scan put my EDD 4 days ahead of my calculations and the sonographer was adamant we would have to go with the new date. Weirdly, my GP asked me which one I wanted to go with and I was a bit taken aback by even being given the choice so I just said I'd go along with the new one.

The thing is, I did ovulation sticks the month we conceived so I know exactly when it happened. We did have sex 4 days before that so if I ovulated early the scan date could be correct but we also did it at ovulation too. Surely the sticks are the most acurate indicator? Anyone know if it's possible to get a positive ovulation result after you ovulate??

On the day of my scan I thought I was 12+3 but the sonographer said I was now 13 weeks. I've read that as time goes by the dating scan is less reliable as babies start to grow at different rates by that stage. We are both tall so I think it may just be that the baby was measuring a bit bigger than average.

I know the EDD is not set in stone (obviously!) but I'm worried about being induced before it's absolutely necessary - and having to listen to people going on about the baby being late!! All the babies in my family seem to turn up late.

Do you think I should ask my GP to move the date back to my original one? I know in the grand scheme of pregnancy woes this is no biggie but I'm thinking about it all the time!!

QTPie Fri 23-Oct-09 16:06:36

If you are worried about being induced, then go for the later (original) due date...

It isn't an exact science... I was convinced that my due date should be 30th Jan (adjusting LMP for length of cycle etc). My first scan (7.5 weeks) said 4th Feb, my second scan (9 weeks) said 3rd Feb, 3rd scan (11.5 weeks) said 1st Feb, 4th scan (15.5 weeks) said 31st Jan, 5th scan (20 weeks) thinks probably about 28th Jan! Originally the MW insisted on 4th Fab as the EDD, but I have changed hospitals and have changed the EDD to 31st Jan: I thik that it more realistic AND my hospital will only accept births from 36 weeks - so an earlier EDD is a good thing for me...


IckleJess Fri 23-Oct-09 19:03:59

My dating scans have always put me a week ahead of my dates - and I always know my exact dates.

I never take any notice of them normally but I did last time (and will do this time too if it happens again) as I wanted a home birth and in my area if you go into labour before 39 weeks they won't deliver you and you have to go to hospital. So, for me it was the opposite of your concerns.

pipWereRabbit Fri 23-Oct-09 19:09:28

No, my dating scan was out by a week (early) and the hospital would not listen to my please to change it to a week later. I was desperate not to be induced early again.

How did I know they were a week early? Because it was an IVF pregnancy and I knew exactly when conception occured.

Luckily, I managed to fend off calls for induction and gave birth on the exact date given to me by my IVF clinic - one week later than the dating scan.

I still don't understand why the staff in the hospital were unable to comprehend when my due date was, I'd have thought it was obvious hmm.

MumNWLondon Mon 26-Oct-09 19:43:10

Mine is around 3 days out - I ovulated on around day 17 and I gave the date of my period which they agreed with (implying 28 day cycle and ovulating on day 14).

If I get to the point of being 14 days late and them wanting to induce I will discuss it then, and be adamant then but I am not so worried as both DD and DS came around 2 days late.

As far as i understand only scans at around 6-7 weeks are accurate (up to 3 days variance)- by 12-14 weeks can be a week out.

jojochanel Mon 26-Oct-09 20:02:27

VanillaIce - I'm in exactly same psition as you. Temp charts and ov kits says ovulated day 21 which is pretty normal for me and my own EDD is 30th March. Scan at 7 and 9.5 weeks both put me due on 29th March. Booking scan in 14th week said I was 4 days ahead of my own date and EDD 26th March. Means I would have ovulated day 17 when negative ov test result and no temperature changes. Trying for a girl so BD on the 17th 4 days prior to when I thought I ovulated. If I ovulated on the day 17 it's probs another boy.

Mine is 2nd VBAC and can't get induced so will have to be section if baby late. I'm not letting them do it until I'm at least 12 days past my own EDD otherwise I'll be getting a section at 40+8. Luckily baby 2 was early so maybe the same will happen this time.

pecanpie Mon 26-Oct-09 20:19:25

My hospital completely ignored the fact that I have a s week cycle not 4 week when they calculated my dates so no I don't trust the dates. Last time, with my dd, I didn't know the length of my cycle and dd was late. Having said that, who said that every baby takes exactly 40 weeks (well, 38 from ovulation) to cook?

VanillaIce Mon 26-Oct-09 21:50:47

My anxiety has now been increased by the fact that we went on a tour of the birthing we're hoping to use at the weekend and they said they won't accept you once you have gone 7 days overdue. With the scan bringing me forward 4 days, this only gives me 3 days over the date I believe is my due date and after that I'll be forced to go to the local hospital instead. The birth centre is so amazing I'd be gutted not to go now. As it's my first baby, I'm sure it'll be at least 3 days late (7 by their reckoning) and then I'm really screwed.

Everyone I've asked has been surprised they changed me in the first place as unless the scan date differs from your own by more than a week they don't usually mind?

Anyone managed to get their due date changed back to the original one? ie. the one they were given at the booking appointment?

onebyoneNOTfourbyfour Tue 27-Oct-09 09:00:43

I'm in a very similar position. My original EDD was 4th May 2010, based on my LMP of 28th July 2009. I wasn't doing any ovulation tests but my periods are very regular and either 27 or 28 days apart. Also, my EDD is a very significant day in our family as it's my late father's birthday and this is my first baby, hence I'm chuffed to bits with the date!

Anyway, went for my Nuchal scan last Tuesday when I thought I was 12+1 only to be told that due to the crown to rump length they reckon I was 12+6 and the EDD is now 28th April. I was pretty upset with that TBH.

Like some others here I'm thinking that because me and DP are both tall, I'm 5ft 10 and he's 6ft 1) bubs could possibly by longer already!! Mayabe it's a mad theory but unless they push me I'm still saying my EDD is 4th May.

katster37 Tue 27-Oct-09 11:30:53

I'm in a similar position - used OPKs and temped so was certain I was due on 25th November. Early scan at 6+5 said 21st November, which coincidentally ties in perfectly with my LMP, but I never ovulate as early as day 14. My 12 week and 22 week scans have both said the 21st Nov too, so I was beginning to think maybe I was wrong, and that temping wasn't as accurate as I had been led to believe. I guess it's only a problem if we are late / early, but it is all v strange.

fiziwizzle Tue 27-Oct-09 14:04:32

Vanilla this is your pregnancy and you are in charge. Insist that your EDD is changed to your date instead of the scan date. Scans are NOT 100% accurate whatever the sonographer says and if your birthing centre only accepts you up to 7 days past due date (which sounds bizarre anyway; why?) then it is important for you that your EDD is changed. Your GP sounds amenable so just do it.

IControlSandwichMonkey Tue 27-Oct-09 14:15:17

Ovulator predictor kits are not utterly reliable.

Scans are not utterly reliable although most babies develop at a very similar rate up until 12 weeks (hence the timing of the scan) and then genetic differences affect growth later.

Regardless of the date, when it comes to the due date, yours or theirs, they cannot force you to be induced. You can be monitored and it is your decision based on the information available to you at the time.

I know exactly when I conceived and was very surprised that all 3 scans agreed entirely with that date. Doesn't always happen, in fact rarely it seems.

reikizen Tue 27-Oct-09 14:24:20

Scans are usually taken to be + or - 5 days, and that is one of the reasons we say a normal pregnancy lasts between 38-42 weeks. However, if you are due to be induced, the hospital will use the scan date, not your lmp or protestations about knowing when you did or didn't have sex (as in my case!) However, that is kind of irrelevant if you are planning to decline induction anyway, and choose to be monitored instead.

TopSop Tue 27-Oct-09 14:37:46

Ditto, OP. I was charting so I know to within 2-3 days when I conceived this time around (after our 20 week scan if we find out what flavour we're having I'd probably even be able to pinpoint a particular day, lol!) I went for my nuchal on the day when I was 12 weeks exactly, but based on baby measurements the sonographer made me 12+6.

TBH my DS was about 9 days late so it doesn't bother me that much - the EDD is just that - estimated, and therefore a movable feast! I know this one will be arriving some time around the end of April or beginning of May. May would actually be better as otherwise I'll be having to hold a 4-yr-old's b'day party with a newborn in tow, or alternatively might still be in hospital.....

GibberingGinger Tue 27-Oct-09 15:24:43

In my experience the hospital tends to go with the scan date. But then again I didn't try arguing very much. My dates were all over the place. If I went with date of conception (which I knew cause we only did it once) I would have been 2nd Jan. By last period date I would have been 6th Jan. By scan date it would have been 12th Jan. She actually arrived on the 22nd Jan! By induction. It was the longest pregnancy ever!
Its definitely worth trying to get it changed if its having such an affect on where you can give birth. Hope it all works out well in the end

puffylovett Tue 27-Oct-09 15:34:41

If you can get your date changed, I would strongly urge you to. With Both of my pregnancies, the scan put me due over a week earlier than I KNEW I was due, based on conception date.

In both cases the stress that I was under at the end of my pregnancies, when I went past 42 weeks, was really high and made doubly worse by all the consultants telling me baby was at risk, could be in trouble etc by going past my EDD. In both cases I held out for monitoring, both boys were born bang on 40 weeks to the date that they were conceived but in the latter case the stress was so high that my blood pressure went through the roof and I missed out on my much wanted home water birth. Like you, DP and I are both tall and also quite well built (strong boned grin)

If you don't change your date, its important to remember that when the consultant says to you 'We will induce on this day', what they actually mean is, 'it's up to you if you would like to accept induction, but it's our policy to induce on such and such a date !'

Join the discussion

Registering is free, easy, and means you can join in the discussion, watch threads, get discounts, win prizes and lots more.

Register now »

Already registered? Log in with: