Why the discrepancy in due dates from online due date calculators?

Discussion in 'Pregnancy - First Trimester' started by flashy09, Apr 4, 2011.

  1. flashy09

    flashy09 Well-Known Member

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    t shouldn't matter as the dates are so close. But I am really enjoying tracking my progress day by day with ipregnancy app and a great book called pregnancy day by day. So I am a little obsessive with whether I am 5 weeks 1 day or 2 days!

    This is my confusion. LMP (2/27) due date is Dec 4th. It's based on a 14 day ovulation. Great, I happened to ovulate day 14 (march 12) so should be totally accurate and easy. But when I go to a site that uses ovulation instead of LMP and put in 3/12/11 I get Dec 3rd? Why the difference if both methods use day 14?

    The Dec 3rd due date makes my baby 37 days according to Ipregnancy, which is my exact cycle day and therefore seems to make sense (seeing that they count from first day of period). So should I stick with Dec 3rd?

    I didn't take my OCD medicine this morning, lol
     
  2. letshaveababy

    letshaveababy Mommy of 4!!

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    First of all, Congrats! We are due almost the exact same time!!

    The simple explanation that I come up with is that most due date calculators go by a 28-day cycle, which puts your date off if you don't run on a 28-day cycle.

    I had my due date as December 4th on a regular calculator, but then when I found one that lets you pick how long your cycle is, my due date was December 3rd.

    Could that be it??:hugs:
     
  3. flashy09

    flashy09 Well-Known Member

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    Well, my cycle is 28 days and I did ovulate day 14 so it all seems textbook. But every site I put my ovulation date in I get 12/3 and every site I put my LMP I get 12/4! If I go with 12/4, then Ipregnancy app says my baby is 36 days but I am on cycle day 37. So confused!

    Congratulations to you too!! Is this your first? It's mine and I am sooo nervous something is going to go wrong but also really excited when not worrying!
     
  4. AshleyNichole

    AshleyNichole mommy to 2 boys!

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    Im not sure I just did a calc. and from my conception day I am 6wks.
    but from my lmp I am 5.1 :shrug: :lol:
     
  5. letshaveababy

    letshaveababy Mommy of 4!!

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    No actually this is my 4th child!! :happydance:
     
  6. flashy09

    flashy09 Well-Known Member

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    Wow thats crazy! How could you have conceived before your LMP? Maybe I will just not worry about ovulation date calculators and go with the Dec 4th like the doctor most likely will.
     

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