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Talkback: Can your pregnancy scan give the wrong due date?


  • Hi Mariarus25. Thanks so much for your post – we always welcome feedback, positive or negative, as we always aim to make our articles as accurate and as helpful as possible.

    We spent a lot of time talking to sonographers before writing this article, so we're surprised that you think what they're saying is not in line with what you have studied. We'd be really keen to know more about your studies – and what you have learned. Perhaps you could drop us a line at [email protected] and tell us a bit more?

    You're right that we did include 'anecdotal stories' in our article. We used them to illustrate the key points we were making in the articles but the quotes we used were all centred on the real experiences of pregnant women posting in our forum. We are confident that we are not using these quotes to 'misinform women', as the key points in our article were all sourced from expert monographers.

    It's interesting that you say that ultrasounds between 8 and 10 weeks are the most accurate. In the UK, most pregnant women don't have an ultrasound until they are at least 12 weeks pregnant. Perhaps you are based in the US, or another country, where ultrasound practice is a bit different?

    Do drop us a line a bout your studies, please. We'd be really interested to hear more.

  • Some of the information in this article disagrees with everything we have studied so far regarding dating pregnancies and ultrasound accuracy. An ultrasound between 8-10 weeks is the most accurate, not 11-14. It's also pretty bad practice to change due dates after the first trimester just because a baby is measuring big/small. Please do not misinform women on anectodal stories.
  • Could a dating scan be wrong when i saw a midwife 4 weeks ago she thought i was at least 16 weeks a scan has now shown im 13 weeks 2 days but my baby is already kicking strong ive also video'd my bump moving very vigorously
  • edited Aug 5, 2019 8:53AM

    Post deleted by MadeForMums.
    Here's a link to our Chat guidelines

  • edited Oct 18, 2019 7:10PM
    Mariarus 25 Stop being a hater. The Drs are so often wrong and every women cycle and body are different. This is the first article that was comforting and refreshing..If your unhappy with the article move on to the next. If I was the author of this of article I would block you from my page. So many people are programmed by the collective unconscious. So many people naturally align with negativity.. pregnancy should be a beautiful loving experience and finding others who feel the same way is very comforting and enlightening. I know first hand the Drs are not always right. They are programmed to follow certian procedures.
  • I have a spot on 28 day cycle and know the only opportunity for me to fall pregnant happened on the 4.7.20 so I would be 5 weeks 4 days I had some spotting so early scan. I had a internal ultrasound this morning and she said 7weeks 2days and no heart beat. I'm obviously upset and very confused.
  • DanielleMFMDanielleMFM admin
    edited Jul 29, 2020 8:14AM
    Nadz13 said:
    I have a spot on 28 day cycle and know the only opportunity for me to fall pregnant happened on the 4.7.20 so I would be 5 weeks 4 days I had some spotting so early scan. I had a internal ultrasound this morning and she said 7weeks 2days and no heart beat. I'm obviously upset and very confused.
    Hi @Nadz13 we are so sorry to hear about what you are going through right now. We have a Chat forum right here where you can chat about what you are going through with others who may be experiencing or have experienced the same. We do hope it helps. Wishing you well. 
  • I found out I was pregnant 2 weeks ago I took a clear blue test it came up 2-3 weeks pregnant my last period was 15th off august and my cycle is 31 I went for a early scan yesterday they scanned 8 weeks at 3 days but no heart beat, why do my dates not add up too the dates they said they are saying my baby is dead but I can only be 6 weeks pregnant?
  • edited Oct 11, 2020 10:17PM
    I love this article! It gave me some peace of mind since I'm experiencing this now in my early pregnancy. I'm gonna relax and just wait till my next ultrasound. Thank you Made For Mums!
  • It's our pleasure, Lalamunchikin. Thanks for your lovely comment! All the best with the rest of your pregnancy!
  • Hi, I am very confused on my pregnancy. Yesterday, I was told I am 8 weeks pregnant with 3 days. The doctor said my date of conception was around October 3-7 or so but when I went to confirm the pregnancy the first time, different location, the doctor said my date of conception was anywhere between September 19-24. September is when I know I had intercourse so I am so confused because it was around the 20th or so
  • Hi @mn12 we're afraid we can't answer your questions, but if you want to come and post your question over on our chat forum, we're sure someone might be able to help. 

  • I had a 5 day IVF FET on 4 th Aug, when I walked out of clinic I was 2 w5d. All the calculators factoring in the FET say I am due on 22nd April 2021. The IVF clinic say 9th April,the scan says 19th April. I think the clinic may have made an error on my paperwork. Which do I go by?
  • If i am due on 9th April then my 12 week and 20 week scan are all measuring my baby up to 2 weeks behind and the sonographer said this will raise alarms but even 2 of my drs don't believe the 9th is correct but they have to put it down as the EDD as that is what the Ivf clinic says.  Can I ask the clinic the clarify or should I push my drs to do this.  This is my first baby and I am a diabetic so accurate dates are quite important.
  • Hi @Simone31051991 thanks for your questions, but we're afraid we can't answer them as we're not medical experts. We do have a pregnancy chat forum here, where you can ask your questions, and we also have an IVF forum here too, where hopefully someone from our community can help. 
  • Hi I had a 12 week scan today. My fates were completely off. In certain the dates are wrong as I know the exact time I got pregnant and who with as there has only been one person in the last year. I counted I would be 13 weeks 4 days but they told me I was 15 weeks 5 days. I am completely devastated as now the partner thinks it isn't his. Is there anyway this is possible they have got it wrong as I'm so confused as to how this is happening. Any help or advice would be appreciated.
  • I stumbled across this article and since many women have questions about their dating scans, this information saying early scans are often wrong is incorrect and can create unnecessary worry and here’s why.

    A dating scan is in fact more accurate the earlier it is done. In the states the most accurate way to date a pregnancy is with an ultrasound done between 6 weeks and 8 weeks, 6 days, according to Dr. Michael Cackovic, MD, an OB-GYN with The Ohio State University Wexner Medical Center. Some other credible sources say between 7-10 weeks. During this time the accuracy can be within +/- 3 days. Babies grow at a pretty consistent rate for all women during this window. When the 12 week scan is offered the accuracy then is within +/- 5 days. At this stage the baby is able to curl up or stretch out which can alter the due date a bit. After 13 weeks, the scans can be off up to 2 weeks.

    Many women claim they know with certainty the day they ovulated but without proper tracking of cervical mucus, OPKS, and a confirmed rise in temperature (which happens after ovulation has already occurred) there is no way to say with 100% accuracy that it happened on said assumed day. (An ultrasound can also confirm ovulation has happened as well but that is costly for some.)

    The standard LMP is just a guideline for doctors until a scan is offered as it assumes every woman has a 28 cycle with ovulation on day 14 and a 14 day luteal phase, which for many woman is not correct. Many women do not accurately remember the start of their period or the correct length or an accurate ovulation date. So Most doctors try to get a dating scan done before the 12 week window to confirm viability, an accurate gestational age, or if the woman is carrying twins etc.

    Another thing that often gets women worried about dates is using an online pregnancy calculator or due date calculator as it is based off the basic guideline of a woman having a standard 28 day cycle with ovulation on day 14 with a luteal phase of 14. It does not account for any issues that could have delayed ovulation (stress, illness, traveling) or give the proper luteal phase which can be 10-16 days long. Again proper tracking of your cycle can help determine the different lengths it can be and give a more accurate window of ovulation.

    This article is based off of comments from women who, if they weren’t properly tracking, can only guess when they ovulated. If you have concerns reach out to your doctor as they know best and with the advances in technology and testing, they can offer reassurance more than an article on the internet.

    For future purposes, women who are wanting to become pregnant or who are actively trying, track your cycle for 3-5 months to establish a better understanding of your own personal Fertile window. Ovulation can occur as early as day 11 and as late as day 22. If you are struggling then speak to your doctor as certain issues such as PCOS or endometriosis can cause late or anovulatory cycles.

  • @Babymakerof3 dating scans are one form of analysis. They are qualitative. Quantitative data (such as bloods) collected over a period of time should also be applied to form more reliable analysis. One or two scans do not, and should not, claim to be 100% accurate.
  • @Babymakerof3 The focus of this article is to present a more complex view of dating taking into account the difficulty within the sonographic field to evaluate purely on visuals. It also takes into accounts of pregnant women who have experienced these complexities. It is a little presumptuous on your part to divert these complexities, placing the blame on women, and the inconsistencies of their claims. One of the editors has already explained below that they have consulted a number of OB’s to support the article.
  • I recently had an early scan at what I believe by LMP 6+4, because of cramping.
    I was told by the sonographer I'm 4/5 weeks not 6+4, although I saw the heartbeat clear as day, which she pointed put to me at first, heartbeats can only be seen on a scan from 5 and a half weeks at the earliest and even then it's hit and miss, also based on a pregnancy being calculated from LMP and when I got my first pregnancy test positive, I wouldn't have even conceived at that point or literally would have that day.
    Inaccuracies are very common at such early scans because every baby grows differently.
    She didn't actually give me a EDD, I guess even she wasn't so sure herself, I'm sure I will find out at my 12 weeks scan 😊
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