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How accurate is ultrasound dating?

I had an ultrasound and they told me at the time I was 15 weeks 5 days. How accurate is that? I am having some concerns with dating and measurements and I want to know the likelihood that the ultrasound measurement could have been up to a month off?

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Asked by kitten_shuga at 5:18 PM on Aug. 26, 2009 in Pregnancy

Level 3 (13 Credits)
Answers (5)
  • Up to a month off is more unlikely than likely. Ultrasounds are much more accurate with dating a pregnancy than they used to be. Why are you concerned about the measurement?

    Answer by sweetmoonem at 5:20 PM on Aug. 26, 2009

  • i do not know but i read that the date of the last menstrual period is often more accurate than u/s estimates so that must mean that they can be off by at least a bit.

    Answer by Anonymous at 5:24 PM on Aug. 26, 2009

  • Id say theyre not very accurate because my Due date has been changed with every ultrasound ive had... my due date at first was Dec 10 then Dec 29 then Jan 4 NOW its Dec 26...

    Also my first missed period was in march but theyre saying thats impossible cause I conceived in April... Who knows

    Answer by firethearson at 5:46 PM on Aug. 26, 2009

  • with my second pregnancy I had no idea when my lmp was, so they did an ultrasound... my first one at 8 or 9 weeks, and my due date was June 27th, then the next ultrasound they changed it.... my son came on the first due date they gave me. The earlier the uktrasound predicts the more accurate. The further along you are the harder it is to predict.

    Answer by Precious333 at 6:00 PM on Aug. 26, 2009

  • A month off would be nearly impossible and I would say that if the baby was measuring a month small or big that something isnt right.

    I had mine today and I am 19 weeks 1 day and I measured 19 weeks 2 days!

    Answer by Jaydin_Makenna at 6:38 PM on Aug. 26, 2009

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