Accuracy of your own calculations

HI Girls,

I am 8+1 today going by my last LMP. I have an early scan next friday with babay bond (so excited/nervous)

I was just wondering if when you had your scans were you right in your own calculations? Or were you back dated at all?

I still cant understand how im meant to go from my LMP and not OV so worried they might back date me a few weeks and il have to wait even longer to tell everyone.



  • I used a due date calculator that asks you to put in your cycle length, as mine is 36 days- way longer than the "average" length. That gave me a EDD of 12th August. However, when I was scanned I was bought forward to 6th August, which is much closer to what it would be were my cycles 28 days

    So in answer, I don't think you can ever really tell!

    14+6 x
  • Going by my LMP I'm 26 weeks today but from scan dates I'm 26+5!

    My midwives are using my LMP to predict my due date though which makes it 5 days later than if I go by my scan dates!

    If you know you ovulate late in your cycle your dates probably will change after your scan!

    Bec 26+5 x

  • I've always gone by my LMP (18 July 2008 - blimey!!!) which puts me at 29+5 weeks today.

    I had two early scans which first put me back a few days and then brought me forward a few days.

    When I had my NHS 12-week scan, she made the dates exactly as I thought - going by my LMP.

    Good luck!

    Julie xxx
  • I thought I was 13 weeks on my scan date but was actually 12+4


  • Goonie I'm the same as you - 5 days out! Going by my LMP I'm 29+1, according to an early scan, which is what all my hospital notes go by now, I'm 27+2 but according to my calculation of when I ov'd and according to my 12 week scan, I'm 28 weeks today or 28+1 (oh and according to my bump size as measured today was exactly 28cm). However, as my hospital doesn't change it if it's less than 7 days out what they have on their notes at your 12 week scan, they've left me as being 27+2. Early scans actually are less accurate - the dating scan is done at 12 weeks or thereabouts as this is the most accurate time to measure.
    The only thing that annoys me about my dates being different to the ones on the hospital notes is that my baby is measuring a bit big (as is my bump) for 27 weeks and they keep telling me I'm due a big baby, when in actual fact it's just that I'm a week further along than they think!
  • I couldn't use LMP because I got pregnant in the first month off the pill - no period for me. So I used the day I thought I ovulated and counted back 2 weeks as an estimate of LMP to use as day 1. And I was spot on according to my 12 week scan!
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