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  1. #1
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    Default Dating scan wrong??

    Has anyone had experience with a dating scan being wrong? And I don't mean a day or two, more like a week.

    This is what has happened. Although I don't have regular 28 day cycles, I do chart and watch my cervical mucous and record when we baby dance. I also often feel pain when I ovulated for. Couple of hours.

    My last cycle, I predicted I ovulated on day 20 - I had ovulation pain, it was also my last day of stretchy mucous and it was also the last day we baby danced. So that would make my due date (I got pregnant) 31 march.

    I had a dating scan today and dates showed as 6 weeks 3 days, whereas my dates show 7 weeks 1 day.

    I am questioning whether the the dating scan is actually correct because according to dating scan -

    - it could possibly mean sperm was living inside for 6 days (that's a while) before fertilization
    - my cervical mucous was well and truly sticky and non existent around the dating scan ovulation date -day 26
    - the other big thing is I got a positive pregnancy test at 3 weeks according to dating scan. I don't even know if that is possible! It would have had to implant then send out the hormone to be picked up...?


    What do you think? Should I change my dates? Should I get a repeat scan later on? Should I just stick to my own dates?

    This is my 3rd child and I've had dating scans for all my babies, and the others lined up with my own dates (by charting).

  2. #2
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    My last pregnancy my dating scan was two weeks off. The day they said I conceived, my period was due. But let me tell you, I gave birth the day before they said my due date was

    mummy to gods gift to us

  3. #3
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    That's only 5 days difference which isn't very much. I have read that some sperm can live up to 10 days if conditions are favourable. Most of the time in my experience and that of people I know IRL they like to use your LMP date at hospital anyway. And you can get a pos HPT as early as a week after implantation.
    Early dating scans are considered the most accurate, later scans not so much. I would just tell the hosp or ob your dates and the u/s dates and let them pick, it's only a small difference. Good luck!

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    Yes my dating scan with ds was over 1 week out. Ds is now 6.

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    The sperm can live for days but the egg will pass through within 24 hours. You were obviously fertilized when you ov'd but the egg too a few days to implant properly I would guess. The dating scan date is the most accurate date but remember that the baby is really little t six weeks and a slight change in how they measure the bub can change your dates.

    Go by the later due date rather than the earlier one. It will mean a great deal at the end of your preg, just in case bub wants to stay in a bit longer. You don't want to be pressured into an induction when you are only five days over, because you went my lmp rather than dating scan.

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    My dating scan was off by at least a week and then my 12 week scan was off by 2w3d. I spoke to my midwife about it and showed her the dates I had worked out and we worked out a compromise date (put me forward by a week more than the first scan). We were only worried about it because I have a history of prem babies and a week or two could be the difference between needing to be transferred to a larger hospital in Melbourne as opposed to delivering at our local hospital.

    She told me that they would normally not change the due date from a dating scan unless the next scan dates were off by at least 2 weeks and your (not you personally, obviously) fundal measurements corresponded to that date.

    I'm still measuring 2 weeks bigger by fundal height but haven't had another scan so we're sticking with our agreed date for now.

    5 days is not a big deal and I don't think they'd even consider changing your dates unless your bub starts measuring small/big for dates.

  7. #7
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    Zombie_eyes is offline Formerly Diamondeyes
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    i read a long time ago that your luteal phase needs to be at lest 10 days long. in order for plantation to occur? anything less and there isnt enough time.

    so if u believe u ovulated on day 20 and have a 28 day cycle that only gives u a luteal phase of 8 days. not really possible.

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    From what i was told with DD2 (there was a dispute about when she was due as different scans showed about 1-2 weeks difference and it didn't match when i thought i conceived and i only had sex once blah blah). Anywho i was told the early dating scan is the most accurate as babies grow at the same rate for those first few weeks so this is the date that was used. In retrospect i think it was fairly spot on.

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    Mine was 5 days behind also (at 6 weeks 2 days). I think there is a large margin for error as the baby is so tiny. I had another scan at 9 weeks (my LMP date) and I was 8 weeks 6 days! At my 12 week scan I was 12 weeks exactly and I measured 11 weeks 6 days. I stayed with my LMP date!
    Last edited by Jackinabox; 14-08-2012 at 00:13.

  10. #10
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    Quote Originally Posted by DiamondEyes View Post
    i read a long time ago that your luteal phase needs to be at lest 10 days long. in order for plantation to occur? anything less and there isnt enough time.

    so if u believe u ovulated on day 20 and have a 28 day cycle that only gives u a luteal phase of 8 days. not really possible.
    The OP mentioned that she doesn't have regular 28 day cycles.


 

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