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Can Ultrasound due dates be wrong?

I had an ultrasound and they dated me at 5 wks. Then I went in at 20 wks and they did measurements. However, I feel like I did like 2 days before I had my son. Could I actually be futher along than 21wks? I have been losing my mucus plug also.

Answer Question

Asked by Anonymous at 7:24 PM on Nov. 3, 2009 in Pregnancy

Answers (13)
  • Wait... you think you are full term but they think you are 21 weeks? No, it cant be THAT wrong! 2 weeks either direction, maybe but not 20 weeks!! I lost part of my plug at 18 weeks... it doesnt mean anything, and it rebuilds itself.

    Answer by Jaydin_Makenna at 7:26 PM on Nov. 3, 2009

  • Ultrasound dates aren't always accurate, but there is no way it could be off 20 weeks!! There is way too much of a difference in the babies development. Maybe 4 weeks off, but not close to 20.

    Answer by micheledo at 7:26 PM on Nov. 3, 2009

  • ultrasounds are highly inaccurate, its an educated guess at what development should be- not what it actually is, every pregnancy is different... it is inaccurate, but not by THAT big a margin. a few weeks, but not a few months.

    Answer by ObbyDobbie at 7:31 PM on Nov. 3, 2009

  • I wasnt thinking 20 wks off I was worried about premature labor, my first i started going into labor around 28-29 wks, I was just hoping that this one wasnt coming too early.

    Answer by Anonymous at 7:33 PM on Nov. 3, 2009

  • That would make more sense! Sorry for misunderstanding you. You could be farther along for sure. Take it easy and call your doctor in the morning if anything else happens.

    Answer by micheledo at 7:35 PM on Nov. 3, 2009

  • the earlier you have an utlrasound the more accurate it will be. The further along you are can be pretty inacurrate because babies grow at different rates etc.

    Answer by Precious333 at 7:39 PM on Nov. 3, 2009

  • Yes, they can be wrong. It was wrong with my second child, I had preclampsia and they had to take him early, they thought it would only be two weeks early...nope they were one month off so he ended up being six weeks early and had to stay in the n.i.c.u. The problem was that when I became pregnant with him my daughter was just 8 months ols and I had breastfed and my periods weren't regular yet so I had really no idea when we got pregnant and just assumed they were right.

    Answer by presleyfan1 at 7:42 PM on Nov. 3, 2009

  • I would be shocked if an ultrasound was that off. My son measured a full month ahead every ultrasound I had (and I had alot with him) but I know my dates with him were correct (my DH then fiance was gone with the Army the month before--- I literally could NOT have gotten pregnant then). I would call the doctor with your concerns.

    Answer by IrishMommaC at 7:45 PM on Nov. 3, 2009

  • I have always had very irregular periods....6 in one year was alot. I also got pregnant regardless of birth control. When i was pregnant with my son, we had no idea of a date....nothing to really go on. The ultrasound said December 7th. He was born January 21st. 10 pounds, 23 inches long.

    Answer by EireLass at 7:48 PM on Nov. 3, 2009

  • ok, now THAT makes more sense... only you know your body, and if you feel signs of preterm labor you should definitely quiet down, hydrate, and see what happens.
    there isn't a lot that they can do for you unless you're experiencing major issues (as you would know, if you have experienced preterm labor before). i hope you're just having an off day... get some rest!

    Answer by ObbyDobbie at 7:50 PM on Nov. 3, 2009

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