What are the odds that you are having a child with Down syndrome?

138th Kentucky DerbyHere in my hometown, it’s Derby week. With the greatest two minutes in sports upon us, it naturally has me thinking about odds. Indeed, prenatal testing for Down syndrome has that same focus. So, what are the odds that you are having a child with Down syndrome? Not only is this answer important, but it will surprise many.

It has long been known that the chance for having a child with Down syndrome increases with the age of the mother. See the graph at this post for the chance based on maternal age. While this relationship has been known, the reason for it remains unknown. Moreover, the most recent guidelines from the International Society for Prenatal Diagnosis (ISPD) state that maternal age, alone, is not enough to rely upon for the chance of having a child with Down syndrome.

This is where prenatal screening comes in. Screening tests provide a reevaluation of the odds that a pregnancy is positive for Down syndrome. Initially these tests could only be provided in the second-trimester. Then, in 2007, professional guidelines recognized the nuchal translucency-combined test, which can be offered in the first trimester.

As an example of these type of screening tests, a mother who is 25-years old has a baseline chance of having a child with Down syndrome of about 1-in-1,250; if she were to receive a screen result for Down syndrome, then her odds may be readjusted to 1-in-250, or some other revision of her baseline chance for having a child with Down syndrome. But, these tests have been likened to “tarot cards” because they are imprecise, with false positives outweighing the number of pregnancies with Down syndrome that the screening tests actually detect.

As has been covered at length on this blog, now we have a new era of prenatal testing known as Non-Invasive Prenatal Screening (NIPS). These tests essentially turn the odds of the previous screening tests on their head. Whereas under the “tarot cards” false positives outnumber true positives, that is not the case for NIPS; instead, a NIPS result for Down syndrome can mean the odds are that the pregnancy actually is positive for Down syndrome (when the mother is 30 years or older–see the graph at this post).

But, as every professional statement and even the NIPS testing companies themselves have emphasized, a NIPS result is not enough to rely upon because there remain false positives and false negatives. Therefore, diagnostic testing is required to truly know whether you are having a child with Down syndrome and only an amniocentesis provides the most accurate results, since CVS testing can return the same false positive as NIPS.

But (and here’s the kicker), even a diagnostic test will not tell you your odds for having a child with Down syndrome.

Here’s why:

Odds are, you are not going to have a child with Down syndrome. There is no maternal age where the odds of having a child with Down syndrome exceed the chance of not having a child with Down syndrome. In fact, almost every pregnant woman in the world is not going to have a child with Down syndrome.

This is because the incidence of actually having a child with Down syndrome is very low. Of the 6 million pregnancies each year in the United States, there are at most 20,000 pregnancies that are actually carrying a child with Down syndrome. But, even for those pregnancies the odds are they are not going to have a child with Down syndrome.

How can this be?

Because most pregnancies positive for Down syndrome naturally miscarry. Reports vary on the percentages, but the ones that I’m familiar with state that 50% of pregnancies carrying a child with Down syndrome miscarry in the first trimester and 40% of those pregnancies that make it to the second trimester miscarry. This means, receiving a CVS result in the first trimester means the pregnancy has as much of a chance of miscarrying as continuing into the second trimester. Once the pregnancy is into the second trimester, when an amniocentesis can be performed, the odds of giving birth to a child with Down syndrome are still 6 out of 10.

So, the odds are that even with a diagnosis for Down syndrome, it does not mean that a child will be born with Down syndrome.

I wonder how often this actually is shared with expectant mothers considering prenatal testing. While it is discussed in recognized resources like “Diagnosis to Delivery,” for those mothers who choose to continue their pregnancy after a prenatal diagnosis, I wonder if it is shared with mothers considering termination?

It certainly would seem relevant that a woman considering an invasive medical procedure would be advised of the possible outcomes if the procedure were not performed. Considering that the whole exercise of prenatal testing is to determine the chance of having a child with Down syndrome, shouldn’t these odds also be shared?

Comments

  1. Hi. We are 20 weeks into our pregnancy and just found out from the materniT21 test that our child has DS T21. So I’m out hunting for information and found your blog referenced by a genetic technician.
    In the above you state, “Once the pregnancy is into the second trimester, when an amniocentesis can be performed, the odds of giving birth to a child with Down syndrome are still 6 out of 10.”
    As we are in our 2nd trimester this is obviously very troubling and I want to understand what we are facing as we continue to carry.

    So I thank you for your efforts and ask if you can point me to the source of the metrics you pointed to above?

    • Abraham–a MaterniT21 test is never positive or negative completely for Down syndrome–there remain false positives and false negatives. To determine your wife’s chances of having a child with Down syndrome following a MaterniT21 test, it would involve applying her baseline chance based on her age with the stated accuracy rate for MaterniT21 (around 99.5% detertion/99.9% specificity). You can follow the analysis at this post or ask to meet with a genetic counselor who should be able to advise you.

    • my daughter tested positive for down syndrome im extremely happy that she had no such thing at birth at all shes smart and going in fifth grade now I almost got a abortion trusting results but felt so bad because I was far along so thank you jesus for this blessing oh I prayed hard I EVEN had a second child 14 monthes later and now 10 yrs later im pregnant again this time worried im 42,

      • Rebekah, when you say your daughter tested “positive” for Down syndrome, I wonder if that was just a screening test. Given your current pregnancy, it is important to know that the only true “positive” is from diagnostic testing, which involves inserting a needle into the womb and removing a sample of the amniotic fluid. Unless you have that test (or a few other similarly invasive diagnostic tests), no other test is truly a “positive,” but just a recalculation of the chances of having a child with Down syndrome.

    • How are you doing now….w ith your downs baby?…We..have a two day old baby

      • My son has,downs. He is 32 on May 1. I was only 21 when I had him which back then was rare. I got him into infant stimulation classes at 2,months. I worked with him every day. Teachers said he could not learn to read but I taught him phonics and he can read anything! It is very important that you work with your child alot. The school taught him signing but then he stopped talking. I did homemade flashcards to get him to talk. I labelled everything in the house to teach him to read, I got him fun reading programs for the computer. Now he cooks, is a good cook, and he can walk to the store on his own, get everything on my lidt, and use a debit card and type in the pin. He went to normal preschool through high school. He went to a career center that taught him to cook and do laundry, dishes etc. We taught him the days of the week by singing the happy days theme song! Over and over and over. I have a daughter born 4 years after him that is exceptionally smart. Craig can do just about anything!

  2. I have tested positive for Down’s syndrome and have to further go on to have amniocentesis . I would like to know where you got your information as I believe you are severely misinformed. There are a lot of women diagnosed with carrying a child with Down’s syndrome . Unfortunately- these tests are alot more indicative of actual results rather than not. I think you need to be doing more research prior to writing about something you are not entirely educated in.

    • Please see the further research I have done on this issue at the post at this link. Read to the end and read the two other posts linked there. Also, feel free to share your amnio results as I would be curious if they confirm the screening test result or contradict the screen result.

      • I had a screening done when I was 22 years old, pregnant with first child, and they said I tested positive, had the amino, and my daughter is perfectly healthy. Even the doctors say the screening is not accurate.

  3. Anonymous Person says:

    Having made the difficult decision to terminate a pregnancy that was confirmed T21 after NT screen and subsequent amniocentesis, I completely disagree with the approach you seem to be taking. I was informed of the percentages of miscarriage, etc. prior to the amniocentesis, and this information in fact, lead us to make the decision my husband and I came to. With a 40% chance of miscarriage, and grave reservations regarding other co-morbid conditions associated with a downs diagnosis, it is imperative to arm women with this information.

    For your comment regarding the Maternit21 test above, I believe its cruel of you to convey such a tone of hopefulness. This test is incredibly accurate, and an positive result is a devastating blow to the expecting couple. While you are correct it is not foolproof 100%, I’d urge you to consider your tone in speaking to couples facing what is truly a traumatic experience – the possibility of carrying a child that will die or face potentially overwhelming health issues through his or her life. The tone of your article is quite insensitive — Especially for those 20,000 pregnancies each year facing these issues. Who else exactly do you think is searching for your article????

    • Thank you for sharing your experience. I try to be mindful that every woman makes her own decision. I just want those decisions, whatever they may be, are based on accurate information. Too often that does not happen.

    • I am a parent of an amazing girl with down syndrome,i didnt have any tests i took it as she was a baby and my baby! I wouldnt change her for the world!
      I think to many people are scared of the unknown and assume down syndrome is this condition that means the child will not reach and milestones or achieve anything?? There is nothing to say you will give birth to a baby that goes on to have any number of life dibilitating problems none of which are chromosome related so i think some of the mums posted on here are giving out bad attitudes to other mums about testing and DS.

      Please look at all the facts and check with other mums in your areas whi have down syndrome children just what life can be like, yes yiu might visit hospital a few more times yes it takes longer for them to learn but in a away you get to keep your baby for longer before they become terrible toddlers with tantrums.
      babies are born healthy in lots of different ways my girl is healthy she just has down syndrome it doesnt difine her shes just a girl x

      • What a beautiful statement Lesley! Yes, some babies are born with challenges, like with my last baby. He was in the NICU for 3 months with many complications. The doctors said we could “pull the plug” if we wanted to. We said NO WAY! Now he’s 3, and has lived a year longer than they expected and functioning in ways they said he never would! Yes, he has limits, takes longer to learn a few things, but knowing his disability, he’s brilliant, and I wouldn’t change a single minute of our experiences with this truly amazing, sweet, wonderful little boy!

        I appreciate Mark’s article, giving hope is something much more rare these days! I think it’s wonderful that his research and the time he has taken to share his experience can bless the lives, and give a measure of peace and hope to families expecting a new arrival!

    • My son was born with downs 32 years ago. Tests can be inaccurate as other have said on here. Some had a down a diagnosis and had a normal child. My son has downs but is perfectly healthy. He is like any other child. Went to normal school graduates. What they tell you about downs babies is not true! My son walks to the store on his own, gets what’s on my list, pays with debit card, remembers the pin! He cooks for me every day. It only takes patience to teach them! He is such a blessing .

  4. ANONYMOUS says:

    Just a short blup… I too was recently dx with a child having Down’s Syndrome (DS). My Maternit21 test came back with a high positive percentage and my amniocentesis came back positive as well. I know these tests are not 100%, but it allows the parents to make important decisions. Medical professionals never gave me information about a DS child miscarrying in the 2nd trimester secondary to DS. Therefore, the incidents of a pregnancy and DS should be assessed on a case to case basis. NOTE: Not all DS children are dx in utero, the screenings and ultrasounds can come back negative for abnormalities as well. Again, each pregnancy is different.

    • Thank you for sharing your experience. You are correct that each pregnancy is unique and should be treated that way. With having a prenatal diagnosis, feel free to review the resources at the Prenatal Resources tab, which are recommended by professional guidelines, particularly if they weren’t provided to you. I hope you find them helpful.

  5. kimberly says:

    I just foind out I am expecting ny fourth child and I am scared because my youngest has down syndrome and i love him dearly….im reading so much on here i dont get whether or not i will this child will be born with ds or not i am hoping for the best outcome and i believe i wouldnt be given anything i couldnt handle but theres so many thoughts running through my head… i will love the baby anyways In just so full of emotions and hopes that all is going to go well and i am 35 years old is this wrong of me?

    • Kimberly: being a parent myself who had a child after our child with Down syndrome, I understand your concern. The rule of thumb is that once you’ve had a child with Down syndrome, your odds for having another child with Down syndrome are roughly 1:100. However, since you had your first child when you were under 35, according to the National Society of Genetic Counselors guidelines (see Table 1) on giving a diagnosis, your odds now are roughly 1:350. I would discuss these concerns further with your medical professional or genetic counselor, and if you’re connected with your local parent support organization, I expect they have staff members or volunteers who could also help you as well. I wish you a healthy and happy pregnancy.

  6. Hi, I was given a penta screen and it came back as 1 in 82 for having a child with Down syndrome. This is still only 1% chance right? I’m 25 and this is my second child, first was born healthy. I’m terrified and have elected to have an amniocentesis. Since this is not the materniti21 screening is it likely this is a false positive? I have been researching everything to do with this screening and it doesn’t seem scientifically accurate. It tests these substances in your blood but other things could effect these substances right; either lowering them or raising them.

    • Brona–you are correct. Penta is of the more traditional-style screening tests, which have higher false positives than cell free DNA tests like MaterniT21. With the Penta screen result, you would now be considered “high risk” and eligible for a covered cell free DNA test if in the United States. Many mothers with a high risk traditional screen result are opting to rely on the cell free DNA test result, particularly where it is screen-negative, to avoid the risk of miscarriage associated with amniocentesis. However, if you wish to know for certain, an amnio will provide you that level of certainty. The Prenatal Resources tab has links for the recommended resources about Down syndrome for expectant mothers if you wish to learn more about the condition. I hope you receive the care and support you deserve from your medical team.

  7. Hi Mark – As a genetic counselor, I do inform patients that some babies with Down syndrome do pass away during the pregnancy. Typically there is a ~30% risk of an IUFD after a diagnosis is made by amniocentesis around 16 weeks. We therefore follow pregnancies with Down syndrome more closely with extra ultrasounds and monitoring in the 3rd trimester. We unfortunately cannot predict which pregnancies will result in a demise and which will result in a live birth. But having testing and diagnosing Down syndrome during the pregnancy can help parents be aware that there is an increased risk for a loss. It also may help providers prevent a loss – if there are concerns about the baby’s growth, for example, then the doctor can induce labor, assuming she’s far enough along. Do you think that people will be less likely to have testing if they know there’s an increased risk of an IUFD if the baby does have Down syndrome?

    • I’m not sure whether they would be less likely to have testing if they knew beforehand of the increased chance of natural miscarriage. I do wonder, though, if moms may consider that their pregnancy may naturally miscarry after a diagnosis when considering whether they should terminate the pregnancy, i.e. choose to “let nature’s take its course” rather than intervene with an abortion.

      • Hi. I am reading this after just finding out today that we have an increased risk of having a baby with downs syndrone. We have been offered an amnio test and are currently weighing up our options. This is baby number 4 for me and I am 37. My two eldest are already adults and i have a one year old. I have always been pro-choice and have thought previously if I found myself in this position that I would consider a termination. Now I am not sure if I could. I found the information you have provided very informative, and it does make me lean towards just waiting to see what happens. So I think your response to the Dr is valid. It may definitely lead more people to bypass a termination and choose to let nature take its course.

        • Thank you. And if you’d like to learn more about living a life with Down syndrome and the supports available to individuals and their families, check out the Prenatal Resources tab.

  8. My wife just delivered our first child who’s diagnosed with ds upon birth. My wife is only 26 and this is our first child, does this indicate particularly high odds for having a second child with DS? Are there any tests that we have to take prior to considering another pregnancy? Thanks alot

    • Omar: your child should have a karyotype to determine whether your child has nondisjunction Down syndrome or translocation Down syndrome. Then, depending on what type of Down syndrome, check either Table 1 or Table 2 of the NSGC guidelines on delivering a Down syndrome diagnosis, available at this sheets nsgc. I would consult with a genetic counselor about any questions you may have.

      The NSGC guidelines also have helpful recommended resources for new parents. I would also recommend as a new parent the American Academy of Pediatrics healthcare Bull AAP, which you can provide to your pediatrician if he or she isn’t familiar with them. Referral to local support organizations is another recommended resource and I hope you were provided your local group’s contact information.

  9. Hi. My husband has two children from his ex-wife. The older one is healthy and the younger one has down syndrom. I’m now35 years old and would like to know how high is the percentage of a second child with down syndrom?
    Thank you in advance for your help.

    • That’s hard to say as the chance for Down syndrome has been researched based on the mother’s age, but there are few studies based on the father’s. Of the few I’m aware of, there is only a statistical correlation once the father is over 40. I would ask a genetic counselor, but I expect the answer will be that it is your age that is more relevant than your husband having a child with Down syndrome.

  10. Hi Mark,
    Your website is extremely informative and I’m glad I found it. I’m very confused about the results from my second trimester quad screening and perhaps you can help simplify all the numbers I’ve read on the internet but can’t seem to make sense of. Not sure if this is relevant to the question I’m asking but my NT scan and first trimester screening were “normal.”
    Anyway, so I’ve read online that the non invasive screening tests identify 80% of women carrying babies with Trisomy 21 and yield a 5% false positive. I had a positive screening of 1:85 risk of Trisomy 21. My doctor explained that I have a little over 1% risk but what does that mean in real terms if the test finds 80% of cases? If I turn out to be one of the 84/85 does that mean I was a false positive? This is what confuses me. If 80% of cases are positively screened what does that mean for someone like me with who’s a higher risk than someone else my age (32). And 80% is such a high proportion whereas 1% seems so low. I can’t seem to reconcile the two in my mind. Sorry if this is a ramble. Thanks so much!

    • No apology necessary, Jen–you’re experiencing the common confusion with screening tests, which, frankly, the cell free DNA screening labs (cfDNA AKA NIPT) rely on in hyping their claimed accuracy. But you are actually understanding your results correctly. The claimed “accuracy” of cfDNA screens is 99+% for both its ability to detect those pregnancies actually carrying a child with Down syndrome and those pregnancies not carrying a child with Down syndrome (I’m not sure where you’re getting your 80%/5% statistics for cfDNA; I have seen that for other types of screening, but not cfDNA, so I’ll use the 99+% quoted by the labs). Here’s how the screen works in a tested population. At your age, you have somewhere around a 1-in-500 chance of having a child with Down syndrome, based just on your age. Given that your NT scan did not increase that chance, then your baseline remains the same (or more accurately is probably even lower, since the NT did not detect the chance of Down syndrome). So out of 50,000 32 year-old pregnant moms, 100 of them will actually be carrying a child with Down syndrome and 49,900 will not. At the claimed 99+% detection rate, that means the test will result a “positive” for 99 of the 100 moms actually carrying a child with Down syndrome and will report a “negative” for 49,940 of the moms not carrying a child with Down syndrome. But that means 50 of the moms not carrying a child with Down syndrome will receive a “positive” screen result just as the 99 of the moms actually carrying a child with Down syndrome. But for the particular mom, there’s no way of telling whether she is one of the 99 “true positives” or one of the 50 “false positives.” As a result, for every one of the 32 year-old pregnant moms who receive a “positive” screen result, they have a 66% chance of it being a “true positive” and a 34% chance of it being a “false positive.” In your case, you were given a 1-in-85 chance based on your screen result. So, as you correctly state, you could either be the one whose screen result is a “true positive” or you could be one of the 84 “false positives.” I hope this helps and whether it does or not, I would recommend you consult with a genetic counselor or medical geneticist to more fully explain your test results.

  11. Hi Iam 21 weeks pregnant. My blood results from prenatal screening said there a possibility I can have my baby with DS. She said there is a 30% chance. I’m going to have another ultrasound to see what’s really going on. Iam 23 years old. My 3year old came out perfectly fine. No problems. I’m worried. I don’t know what to think.

    • Johanna–it depends on what type of prenatal screening you had. If it was the quad screen, your chance of a false positive still outweighs your chance of having a true positive screen result. That applies as well for if you had the newer cell free DNA-type screen like MaterniT21, Harmony, or one of those. The only way to know for certain is to have an amnio or wait until delivery.

      • Hi Mark,
        I am currently 36 but conceived at 35. I am now 26 weeks. I had 2 soft markers on my ultrasound fetal pyelectasis and EIF. These markers which I was told are also found in healthy ‘normal’ babies can resolve in the 3rd trimester but it sparked them to have me take the materniti21 test which came back positive. Everything else is fine as far as growth. We had a fetal echo which looked great. I never had the NT test bc I was too far along and they couldn’t do it but I was curious what my odds are? They told me I have an 80% chance that she has Down syndrome. I just don’t understand where that 80% is coming from. Is it all the risks combined or is it from the blood test? We are not going to do an amniocentesis. It doesn’t matter to us if she does have downs but of course it’s not what we had pictured for our lives. I have a completely healthy 10 month oLd right now. It’s all just so hard to swallow. Please help?

        • It sounds as though your providers are basing the 80% chance on what your positive predictive value would be based on your age. You can use this calculator at this link to see for yourself. A mom who conceived at 35 who receives a screen-positive cell free DNA screen (like MaterniT21) has an 80% chance that the result is a “true positive” and a 20% chance that it is a “false positive.” For more on PPV, see this fact sheet. All major medical organizations recommend that patients receive written information about the tested-for condition when receiving a screen positive cfDNA screen result, with the Lettercase booklet being identified as the resource to be provided. Your provider can order a copy for free, you can view the booklet on-line, or (best case) your provider orders several to have in stock for other patients. All of that can be done at the Lettercase website. Because you express an intention to continue your pregnancy, then there is another resource recognized for those moms who decide to continue. Diagnosis to Delivery is a book written by moms for moms and deals with the specific issues that surround having a prenatal result. While your test result remains a “maybe,” i.e. there remains a chance that your child does not have Down syndrome, you may still find the book helpful as you consider the chance of having a child with Down syndrome. The book is available for free as a .pdf or you can order a hardcopy from the Down Syndrome Pregnancy website. Lastly, local Down syndrome support organizations are another resource that both professional medical organizations recognize as being helpful for expectant parents and that expectant parents report finding as a source of support. You can find your local organization via this website. I hope this offering of resources is taken for what it is, to be helpful, and not to further overwhelm you. I wish you a healthy pregnancy and birth of your child.

        • Hi Mark,
          I was wondering if you could comment more on the role of soft markers in the diagnosis of Downs. There appear to be so many babies born without chromosomal defects despite the presence of multiple markers on their ultrasounds, yet practitioners are still required to mention that there is a connection. My fetus has two markers (EIF & a mildly dilated kidney), and I received a “low risk” from the Harmony test, but I can’t get the idea of DS out of my head. I’m 36 weeks along and finding myself frightened and distracted solely because of these findings; wishing I hadn’t heard that they had any connection to chromosomal issues in the first place. I know the odds are well on my side, but I just can’t seem to find solace in the unknown. The harmony test accurately determined his gender – does that mean there’s a likelihood that it accurately assessed his risk for DS as well? Thanks.

          • Per the most recent guidelines, ultrasound findings of “soft markers” are to be followed up with serum screening, if that had not yet been offered. In your case, you’ve already had serum screening via the Harmony test, which is screen negative. While there remains the chance of a false negative, the Harmony result is more reliable than the ultrasound findings.

  12. manuel Gonzalez says:

    my wife and i are having our 3rd baby we have a 6 year old girl and a 3 year old boy, our son was born with DS our first my daughter is normal but we just got word that our soon to be born has a 1 in 29 chance of been born with DS and my wife is devastated she really broke down when she got the blood results now our son was a 1 in 3 chance this one is different we are both 34 years old. she is 4 and a half months and this was only the blood test that she got back we still have not done the ” ambio” i apologize if miss spell the name, my wife does not want to do that test she did it the first time and she hates it. Please tell me what are the odds of having another child with DS. thank you

    • The rule of thumb after having a pregnancy positive for Down syndrome is that your baseline chances in subsequent pregnancies are 1-in-100. Without knowing what type of blood test you were given, I cannot confidently say what your adjusted chances are. I would ask your provider if the 1-in-3 chance you were quoted is the “positive predictive value.” If your provider is not aware of that term, he or she can learn more at this link. Here is an on-line calculator that may also be helpful in determining your chances.

  13. Amanda Shine says:

    My harmony nipt produced a result of 95% risk T21. This is slightly less then typical +ve results. I am 12 weeks gestation and awaiting my cvs results.
    I have been advised by my doctor to wait for the karyotype before making decisions/ taking action.
    Why were my harmony results less conclusive then typical? Are you able to advise. We are facing agonising uncertainty.

    • I think you have overestimated the accuracy of tests like Harmony. They are almost never 99% accurate and your chances based on a screen positive is relative to your age, with the lower the age, the lower the actual chance, e.g. a 30 year old mom getting a screen-positive Harmony result still would only have a 50% chance of having a child with Down syndrome. These tests are just screening tests and are never truly positive or negative. The only way to know about that is through diagnostic testing. To find out your actual chances based on your age and more about these tests, see this post and links in it.

  14. I’m in my 3rd trimester now an my doctor did a test screening,told me my child was at low risk of having Down syndrome. So dose that mean my baby will have Down syndrome?

    • An I’m at the age of 23

    • That means the odds that your child will have Down syndrome are low, i.e. unlikely. What those odds are depend on your age and what screening test was done. Given that you are 23 and you have a screening test which your doctor is interpreting as low risk, then that would suggest you have a very low chance that your baby has Down syndrome–lower than just your already low likelihood given your relative young age.

  15. Elyse Avelar says:

    I recently went through my NT scan (blood work and Ultrasound) to check for abnormalities and Down Syndrome.
    I am only 26 and have no family history of it- nor does my husband… i got a call the following day… I tested POSITIVE for down syndrome. …. my heart sank. I dont really know what else she told me- but i do recall having to ask what my chances where. thats when she said ” 1 in 59″… anyway- i made an appointment to see the Genetics Counselor to go more in depth with my results.
    She told us that there is a 98% chance the baby is completely fine- and only 2% (2/100) chance the baby has DS. They suggest a few additional tests to check including the amnio and some type of cervix scrap- also to get the babys actual DNA. I said heck no…. however, I did go for another blood test that is to specifically check the babys chromosomes for the extra one that causes DS… (InformaSeq)
    I know the Genetics Counsleor said we should be fine- but I still cant help but question all of it. My babys neck fluid was good, 1.2- as far as the blood test, she said they test two proteins and i was low on one of them. (.17) and the other I was exactly where i should be.
    Could you give me any more feed back, clarity or additional advice. should I be worried? I am waiting for the results of the informaSeq and I am terrified.
    This is our first child.

    • I’m surprised to hear them state the likelihood of Down syndrome even at 2/100 given your relative young age and that it is based only on a NT-combined screen. Nevertheless, InformaSeq is a more accurate screen, but it does not test the baby’s chromosomes as covered at this post. Ultimately, the only way to know for certain is with an amnio, however, should your InformaSeq come back negative, many women are choosing to rely on the relatively low chance of a false negative instead of taking on the risk of miscarriage associated with an amnio. Should your InformaSeq come back screen-positive, again, it can still be a false positive, and the only way to know for sure is with an amnio. If your InformaSeq comes back screen positive, professional guidelines recommend you receive written resources and referral to support resources. You can find those at the Prenatal Resources Tab on this site.

      • Elyse Avelar says:

        Do you think the 2/100 odds are too low given my age?
        I have been seeing a lot of people with higher odds- and older than me. I did not understand that since the Genetics Counselor stated that a low PAPP-A wasn’t such a big deal and she believes the baby would be fine.

        • The way you relayed the 2/100 odds, that is what is considered the positive predictive value (PPV), i.e. the likelihood that your child has Down syndrome. Actually, though, having rerun my own calculations based on estimates of the accuracy of the NT-combined and your maternal age, your PPV would be 2% based on the NT-combined. Because the chance of having a child with Down syndrome increases with the mother’s age, that is why you’re seeing higher odds with older mothers–because PPV is a reassessment of your baseline chance for having a child with Down syndrome based on your age. As your Genetic Counselor advised you, based on the NT-combined result, you have a 98% chance that your child does not have Down syndrome. The InformaSeq will provide a further revision of these probabilities.

  16. Mark,
    I posted back on Feb 26th, 2016. I wanted to update you on the soft markers. I am now 31 weeks and the markers have dissappeared (pylectasis and EIF). In your professional opinion would this lower my risk? The baby’s growth is perfect and they do not see any other problems as of now. I just can’t stop obsessing about this and can’t wait until our sweet girl gets here. I just thought I would see what you thought. I appreciate all of your feedback. Thank you.

    • Thank you for following up. Just so you know, I’m an attorney and bioethicist, so my opinion should not be relied upon for professional medical advice. That said, I do not think the resolution of the anatomical soft markers have any bearing on whether your child has an extra 21st Chromosome (the cause of Down syndrome) or not. I would still put your PPV at 80% based on your MaterniT21 result. I hope the resources I linked to in my earlier reply were helpful and that your medical team has been supportive as you have continued your pregnancy. I wish you a healthy delivery.

      • Mark,

        I followed this post through my whole pregnancy. My percentage with maternity 21 testing was 80% chance she had DS. My baby was born this past Monday 5/23/16 @ 1136am and it was confirmed at birth that she indeed does have down syndrome. She is healthy as a horse and she is beautiful. I wanted to thank you for all of your knowledge and for sharing it with us.

        Keri

        • Keri–I’m glad to hear that what has been shared here was helpful–really the reason for doing this! I’m also glad to hear that your daughter is doing well. Every child is different just as we all are, so there is no set path. However, I do share about my daughter so that it’s a vision of what life can be like, at least for her. This past Sunday, we attended her third dance recital and yesterday, we attended her graduation from Elementary School. Here’s a post on her dance recital from 2014 with video of her performing. I hope you have similar happy times to look forward to with your little girl.

          • Thank you so much for sharing that with me. She is an amazing dancer! Congrats to her on the photo contest too, that is a wonderful accomplishment. I have no doubts for my baby girl! I know she will move mountains. I will get her involved in as much as possible. I can’t wait to see how she will flourish. Thank you again for the information throughout my pregnancy. I was rather obsessed with reading and learning as much as I could and your blog is one I kept coming back to. Thanks again!
            Keri

  17. Katie Lindsey says:

    I am 25 years old and had an average nt measurement of 2.96 the doctor really scared me and started telling me this probably means our baby has down syndrome or one of the trisomy’s I’m worried we did the inmoraseq test and waiting for results

    • Your doctor is incorrect. At your age, the NT screen would not result in a more probable than not recalculation of the chances you are having a child with Down syndrome. When you receive your cell free DNA screen results, use the links at this post to determine what your chances are and to find resources that should be helpful for you and your doctor.

  18. I’m 26 and the screening came back positive. just like everyone eels, I’m nervous that the child will have ds. the doctor did tell me that there is a very low risk of having ds. I’m going to the specialist to find out more. I’m very worried

    • At your age, a screen positive result would mean you have a 47% chance that it is a false positive. Please see this post and the links in it for helpful resources to understand your test results and supportive resources about Down syndrome.

      • would it come out positive if the due date is wrong?

        • It depends on what test you had. If you had conventional screening, like a Nuchal Translucency or a quad, then, yes, the gestation date is factored into the algorithm. With cell free DNA, not so much, since the primary driver for accuracy there is how much cell free DNA from the pregnancy was included in the sample–though the later the pregnancy, the more accurate cell free DNA screening is precisely because there is more cell free DNA as the pregnancy goes along.

  19. Hi Mark. It took quite a few hours of surfing the web before I stumbled across your page, but it was worth the wait to find it.
    My husband and I decided 8 years into our marriage to try to have a child; I was 35. I already had concerns at that time because of my age, and because of various health problems (IBS and severe arthritis throughout my body). About a year after we made the decision, my husband fell ill, so after a few years I figured it wasn’t in the cards. Imagine my surprise when last June (at age 40) I found myself pregnant. I had a lot of problems from day one: constant pain, and an overwhelming feeling that something wasn’t right. They did the quad testing and kept telling me that everything was “fine with the baby”, but didn’t really seem all that concerned with my overall physical health. My husband and I insisted on amnio (even though they kept asking me if I was absolutely sure I wanted to do that since all the bloodwork they did said everything was fine), along with the FISH test. When they got the results of the FISH test they told us there was a high probability that the baby had Downs, but to not get too concerned until the final results of the amnio. Two days later it was confirmed the baby had Trisomy-21. We decided to terminate the pregnancy. 2 weeks later when the clinic preformed an ultrasound before the procedure, we found that the baby had already passed.
    I have major concerns about trying to have another child, and everyone seems to have different numbers as far as the odds of this happening again. I don’t know if I can go through that heartbreak again, especially since I’ll be 42 in a few months. I know a lot of women are conceiving later in life, but I have to wonder if the ones who are having successful pregnancies are in good health overall, or if that even matters. A lot of places online don’t mention how the women are health-wise, just that they are a(n) “advanced maternal age”.
    Thanks for reading my ramble, any advice would be greatly appreciated.

    • I am not aware of other health issues being related to the incidence for Down syndrome. Therefore, based on your age and having had a previous pregnancy positive for Trisomy 21, according to the National Society of Genetic Counselors (see page 3, Table 1, column 1), your chances are 1.7 times your base-line, age-based chance. Based on an age-based chance at 42 of around 1:65, multiplied by 1.7 (for the previous pregnancy), your revised baseline chance is around 2.6%. That said, I would recommend meeting with a genetic counselor about pre-pregnancy counseling to ask this and other questions you likely have.

  20. Hi Mark.

    My wife is 12weeks pregnant and after an ultrasound where the doctor can’t see any nose bone and the fluid between the baby’s nape and the skin is thick, he suggested CVS. My wife also had blood test and it came back high risk for ds as well. The FISH results from the CVS came back positive. Is there any chance that the tests are false positives? How accurate is the CVS test really? Because we were told that it’s a 100% accurate. Should we go for Amniosintesis? Hope you can provide us some light

    • CVS is not 100% accurate. It tests chorionic villi from the placenta which can be cells that develop into the fetus and cells that develop into the placenta. Therefore, the test result could be of cells from the placenta with Trisomy 21 (Down syndrome), or it could be that your child has mosaic Down syndrome, where only a portion of the child’s cells has an extra 21st Chromosome. FISH results are to be considered screen results only and not diagnostic. CVS is considered diagnostic, but it does have some false positives. At the same time, amniocentesis can also have false positives, but at a much lower rate. The most accurate test is amnio.

  21. Very interesting blog thank you. We are expecting twins and have been given a lower risk for downs of 1 in 386 and 1 in 382. I was wondering though if there is any correlation in risk in twins. We have also been told that it is most likely that they are not identical.

    • Due to the incidence of twins being so low, coupled with the low incidence rate for Down syndrome, there just isn’t much out there on twins and Down syndrome. But I am not aware of there being any correlation in risk in twins.

  22. Today was by far the scariest day of my life. I receive my blood results from my genetic testing and the DR told me I have 1 in 68 chance of having a baby with Down syndrome. I’m 24 and this is my third child. I’m a couple days shy of 17 weeks. I’ve never had any concerns with my previous pregnancies. I have a high level ultrasound scheduled for next Friday 8 days from now. how could by blood test be wrong? I heard that the blood test could be a false positive but how could it be wrong? How could they get the chromosome count incorrect??

    • It depends on what test you had. But whatever test you had, you had what is called a screening test. Whether you had a conventional screening test of the nuchal combined test or one of the cell free DNA screening tests, being screening tests, they each have false positives and false negatives. As such, while they are testing either chemicals in your blood with a correlation to the chance for Down syndrome, or, in the case of cell free DNA, testing DNA that may be from the fetus or may just be from the placenta (see this post here for that explanation), there is a chance that their calculations are off. Based on your Doctor saying you have a 1-in-68 chance, that means you have a 1.4% chance of your scree result being a true positive and a 98.6% chance of it being a false positive. The odds are in your favor that your result is a false positive.

      • After my level 2 ultrasound 2 soft markers were detected one on the heart and the other on the bowels. My risk increased to 20% according to the Dr for DS. I declined the amino to wait for the Maternit21 results to come in. Well today they did and I am now “positive for DS” the obgyn said the test is 99% accurate and expect the worse. I’m scared of the unknown. Should I in fact expect for my child to have DS?

        • Tests like MaterniT21 are almost never 99% accurate, in the sense that no matter their results, it is the rarest of cases when it means you have a 99% chance of having a child with Down syndrome (see this post here). However, if your earlier results that you reported were based off of a conventional screening test, then using that 1-in-68 ratio results in the chances that your MaterniT21 test result is a true positive being 94%, with a 6% chance of your result being a false positive. Put another way, you have a 94% chance that your child has Down syndrome. You can find the calculator and more explanation about this at this post. With your test result, you should’ve received patient support information about Down syndrome. You can find those recommended resources at the Prenatal Resources Tab.

  23. I am 37 and pregnant with my 4th lost my 3rd due to miscarriage. I had 2 normal pregnancies in my 20s and so far my pregnancy has been easy (knock on wood). From what I understand my chances of having a baby with ds are 1\186 chance, I am really scare that my hypothyroidism might make my risk factors even higher. No matter what happens I will love the baby no matter what I am just extrelly worried.

  24. Whats my percentage to have a ds baby if im 21 and i only had the blood test

    • It depends on which “blood test” you are referring to. If you are referring to AFP or a first trimester serum sample combined with a measurement of your fetus’ neck, then whatever the result, you have a very large chance of any screen positive being a false positive. If you had one of the newer cell free DNA screens, like MaterniT21 or Harmony, then the chance of a screen positive being a true positive is 49%–meaning you have as good of a chance that it is a false positive as it being a true positive. You can find out more at this post and the links therein.

  25. Marie White says:

    I am having a difficult time understanding the Panorama Risk Score. My positive predictive value came back at 91% and the fetal fraction was 10.8%. The panorama risk score is >99/100. Does that mean that the chance for baby to have trisomy 21 is greater than 99 out of 100???

    • Marie White says:

      Also, the dr attempted to check for nuchal translucency. He was never able to get the baby in full profile, but did a transvaginal ultrasound and tried to look that way. Is it still accurate if the baby was not in profile?

      • It sounds as though what the report was relaying is that the 91% is your positive predictive value (PPV), i.e. the actual chance that your result is a true positive versus a false positive. See this post here and the links in that post on why these tests are almost never “99% accurate” and a calculator where you can enter your age and find out your PPV. I can’t answer the question about the nuchal scan, but regardless, a Panorama result would take precedence over that scan for the conditions that Panorama tests for.

        • Marie White says:

          Thank you so much for your reply. I went to the calculator on the link and calculated the PPV. Can you tell me what makes this number different than the PPV that panorama listed on the report? Panorama report said 91% PPV and calculator via the link said 75%. What causes the disparity between those values? Thank you again for your reply in this difficult time.

  26. Hello- I recently received a level 2 ultrasound and everything looks great with the baby except they said the nose bone was at 4.8 and it should’ve 5 or greater. They proceeded to tell me that my odds of having a baby with down is 1:10. I’m 36 years old and have two girls prior with nod own syndrome.
    I thought based off of this one thing that was done through an ultrasound seemed to increase the odds greatly. There were no other markers. what are your thoughts on this data that they have provided me with?
    I don’t want to do any testing, however that 1:10 has my mind running wild.
    Thanks

    • Nasal bone measurement is considered a “soft marker” and not recognized for an accuracy to base a 1:10 chance off of alone. I wonder where they got that from as it isn’t recognized in any professional organization’s guidelines for prenatal testing. I would challenge them on what their basis was for that risk score.

      • So based on your experience the odds would be more in our favor? Some research that I have read says that a shortened nasal bone is considered a “hard marker”, do you find this to be inaccurate based off of your research? I will definitely challenge them on this as I do have many questions.
        Thanks for your response.

  27. Hi, when I was 21yrs old I had my first child. He was born with DS. I was tested then and did not carry the gene for DS. At 31 yrs old My second child was born a heathy baby girl with no special needs. My husband and I tried for a 3rd child a year later and we miscarried at 18weeks. She was also downs. I had my chromosomes retested and still negative for the downs gene. Why do I keep having downs babies if I dont carry the gene?

    • After having a child with Down syndrome, the chances of having another child with Down syndrome increase. Plus, as you age, your chances for having a child with Down syndrome increase. I would expect the combination of having had a child with Down syndrome and then a decade elapsing between your third pregnancy likely explains the increased chance. That said, your chance is still somewhere around 1% or a little higher. A genetic counselor could counsel you on your future chances for having a child with Down syndrome.

  28. sonumaddythakur says:

    My wife is 27 year old and during pregenecy of 14 weeks quadple test shows increase risk of down syndrome as tri-21 1:98 and age risk 1:1192 should be go for aminocentesis?
    and also explain how much % risk is there for down syndrome

    • The quad test, while it is an indicator of high risk, has far, far, far more false positives than true positives. If available, you may wish to consider having cell free DNA screening and then decide whether to risk a miscarriage with amniocentesis.

  29. I have question about my 1 st trimester screening results. DSR- aldough within normative range- is at intermediate level beging definded as Duwn syndrome risk between 1:300-1.1000 . An intermediate risk is susceptible to significant up – risking or singnificant down- ruskingdependi g upon the result of corelative screening studies such as modifier sequential screen, fetal DNA in material serum .how can I understand the test results?

  30. Hi Mark,
    I’m 41.9 years old with the history of one miscarriage at age 41. I am pregnant again and 18 weeks now. I just received my SIPS results and it is positive screen for DS (1:110). My health practitioner missed the Nuchal translucency. So, my results are only based on the first and second semesters blood testes. I am very shocked, confused, and heartbroken. I read many posts that there could be a false positive, but I am still very hopeless. I had NIPT test a few days ago and still waiting for the results. I also had a detailed ultrasound on 17 W and 4 days (after getting my SIPS results) and no abnormalities was found.
    I searched a lot to find a website to calculate my odds myself for SIP but I do’n seem to find the one. I’d appreciate your comments about my situation.
    Thanks

    • I’m unaware of a calculator for a SIPS result, but the published accuracy rates for Serum Integrated Prenatal Screening (SIPS) is around 85% detection with a 5% false positive rate. That does not mean you only have a 5% chance of a false positive–it means 5% of all SIPS patients will receive a false positive. From your report of 1:110, that means you have a 0.9% chance of actually having a child with Down syndrome and a 99.1% chance of it being a false positive. The screen report of 1:110 is actually longer odds than just your baseline chance based on your age, which would be around 1:70 or so.

  31. Kayla/worried first time mommy says:

    Hi. So I’m 23 years old expecting my first baby. I had the NT done and the quad screening done in the first and second trimester. The first one came back good but after the second one it shows that I have a positive risk of the baby having Down syndrome. (1/100) I am worried because of how young I am that it came back positive at all. Is the false positive rate higher for me because of how young I am? And if so what are the chances of it being a false positive. I tried to use the ppv calculator but haven’t had any luck because I don’t know if I’m using it right? And is it true that there are a lot of false positives and that most baby’s are ok despite it being a positive risk? Thanks

    • It appears your quad report came back with a positive predictive value (PPV) of 1/100, i.e. that you have a 1% chance of actually having a child with Down syndrome and a 99% chance of your result being a false positive. Considering that disparity in odds, the odds are vastly in favor of your result being a false positive. Your relative young age would inform the PPV analysis, but if the 1/100 is the PPV for the test, then your age was already taken into account. You may want to confirm with your provider that the 1/100 is the PPV for the quad test. If so, then you have a 99% chance that your result is a false positive.

  32. I have 2 daughters. 15 and 16. My youngest has Down Syndrome. I was 18 and 20 when I had them. I had the normal tests done when i was pregnant and everything came back normal. I didn’t know she was down syndrome until I had her. At first I was in denial about it. I was afraid. I did get very angry at a nurse one day for asking me if I knew she was Down Syndrome while I was pregnant would I have aborted her. There was no way. She was my baby and I loved her. I would not change her for anything in the world. She is the most loving and funny kid. She definitely has a personality to her. Yes she does go to the doctor often and has some health issues. But I am her mom and will protect and take care of her any way I can. So I am saying this to any other mother that is pregnant with a baby with Down Syndrome, please don’t even think of abortion. Please don’t pick and choose what child you think is best for you. They are such a gift. There is no love like no other than the love of your child, especially with DS. You are their protector, no matter the diagnosis.
    I am now 35 years old and 6 weeks pregnant. I don’t want to sound like a hypocrite but I am worried about having another baby with Down Syndrome. My daughter does take up most of my time and attention but I wouldnt have it any other way. I’m just worried about the health risks that come with DS…not myself but my baby.

  33. Kayla/ worried first time mommy says:

    Ok so they said the same thing you did. They said the chance of my baby having Down syndrome is 1%. So that is reassuring but they still wanted me to take the maternit21 test and I did and am waiting on the results of that. I’m just kind of scared of getting another positive though. What are the chances of the materniti21 being a false positive for my age. With the chance of 99% that the baby doesn’t have Down syndrome I feel like as you said thats pretty good odds that my baby doesn’t. So I’m just kind of wondering what your thoughts are on that?

    • The 99% false positive chance is more an indicator of the lack of precision for conventional serum screening. MaterniT21 has a much higher detection rate for Down syndrome. Therefore, a screen negative result will mean a greater than 99% chance that your child does not have Down syndrome. A screen positive result would mean a 92% chance that your child has Down syndrome and an 8% chance that the result is a false positive, based off of your recalculated chance of 1/100 from your conventional screen.

      • Kayla/worried first time mommy says:

        Ok thanks for your help. So just a personal question. If it was you waiting on this test result would you feel as if there is a lot to worry about? Because I’m the type of person where when it comes to this kind of stuff I over stress and I know it’s not good for the baby but I would really like your honest opinion as if you feel I have a lot to worry about

        • A difficult question for me to answer fairly. We did not undergo prenatal testing and my wife has said she was glad because she would have worried no matter the result. At the same time, when we learned postnatally that our daughter had Down syndrome, I was very sad and grieved for quite a while, worrying about what life would have in store for my little girl. It has only been in the experience of raising my daughter that I came to meet many other children and adults with Down syndrome, gain a better understanding about what their lives are like, and realize that all the things I worried about for my daughter are things that are years off in the future. By the time any of those concerns could happen, like where will she live, will she have a good job, and what can we do to minimize the risk of sexual assault (my worst fear), we will have parented her and lived with her for years and thousands of hours. Hopefully, having that time to prepare, we will be ready to handle whatever challenges come. I share all this just to say, if I were in your position, I would worry, because I did worry, but it’s only with the passage of time, the realization of how much support there is out there for my daughter and others like her with Down syndrome, that I now barely worry and instead revel in enjoying her grow up into her own person.

  34. Hi Mark, I’m 28 years old and pregnant with my second child. I had my first child at a very young age and in the time that I was pregnant with her, these types downs testing was not really done In SA so we never knew about these test during my first pregnancy, my daughter was born in 2005 and is perfectly healthy and very clever. Now that I am pregnant again, I had to go for an NT scan in my first trimester (which was not done with first pregnancy) everything came back normal accept the neck thickness which was 2.8mm because of that I had to go for downs blood screening and went to see a fetal assessment specialist yesterday, she gave me the blood results and the papp-a result were not to good but the hcg was fine, they gave me a 1:96 result based on the blood and NT results, we then did a complete level 2 scan and she scanned from head to toe saying she is happy with everything but then said at the end that there is a small white spot on the heart and colon. Which then gave me a 1:16result I then did amniocentesis and will have to wait 3 weeks for the results but in the meantime I am so stressed out about everything. What are the chances that these test excluding the amnio could have been false and what are the chances that the white spots on the heart and colon can actually be nothing as this is the first time that they actually picked that up?
    Am I possibly being stressed out over nothing and maybe the doctors these days try and make a diagnosis too soon? Or pick something up on scans that might have nothing to do with down syndrome?

    Are all these test really being done correctly with so many false positives?

    Regards
    Verushca

    • Verushca–the nature of screening tests, like the nuchal and the ultrasound, are that they are not definitive, so they always have false positives and false negatives. In your case, your providers quoted you the odds of around a 1% chance your child had Down syndrome based on the nuchal, which means a 99% chance that your child does not have Down syndrome. I’m not sure what they’re basing the 1:16 result for just the ultrasound, but even that is only a 6% chance of actually having Down syndrome and a 94% chance your child does not have Down syndrome. Anxiety is also commonly associated with screening results. I’m not sure how common or rare the ultrasound findings are for other children, but any ultrasound finding is simply a “soft marker,” meaning one that is associated with a condition but one that cannot be relied on as a true indicator of the condition. I hope the amnio results provide you certainty.

  35. Hi Mark!
    I just had my first prenatal appointment and was asked if I wanted to have the first trimester screening done. I’m 25 and I just want to know what exactly I’m looking at as far as the chances I will have a baby with DS. I know the odds are 1:1250 but what percentage am I looking at?
    Thanks

    • Given your age and provided there are no other factors, e.g. prior aneuploidy miscarriage, sibling with aneuploidy, then your chances of having a child with Down syndrome would be 0.08%, with a 99.92% chance that you are not having a child with Down syndrome. Those percentages are based just off your age. If you had screening testing, that would recalculate your chances.

  36. My wife is pregnant since 8/27 and I am wondering if there might be some miscalculation based on the “weeks” of pregnancy which might throw the blood test for T21/T18/T13 calculations off. She been tested for 1:55 for T21 yet she is only 27 going on 28 when delivering the baby. Might I ask how are the weeks calculated for term? From my calculation its only been 15 weeks when she took the blood test and shouldn’t the blood test for AFP, hCG, T21, T18 and T13 be taken during week 16 ~ 18? Would the earlier test throw the figures off? Thanks

    • I believe the quad test is recognized for the aneuploidy conditions such as Down syndrome, but, that being said, appreciate that the quad result means your pregnancy has a 1.8% chance of actually being positive for Down syndrome and a 98.2% of being a false positive.

  37. I’m 44 and this is my 8th pregnancy lol.All seven were born vaginally, healthy,zero problems whatsoever I wasn’t 44 tho either 🙂 my baby will be 9 in march .I’m about 7 weeks haven’t been to the docs yet and I can only imagine the he’ll I’m gonna catch from the ob docs when I refuse any and all invasive precedures ..I personally think an amniocentesis is just one more risk factor to add to the list ..I say no ty ..I wonder tho if there’s percentages and numbers on the amnt.of pregnancies that have been adversely affected by the test itself..I doubt very seriously there’s a reliable count .what do you think?

    • Congratulations on your pregnancy. The historically quoted number is that amnios have between a 0.5% and 1.0% chance of miscarriage associated with them. However, the more accurate number is the rate experienced by the doctor actually performing the procedure and the rate at the facility where the procedure is performed. Like anything, the more experience the doctor and facility have, the lower the rate of miscarriage.

      • Hi I’m 16 weeks pregnant, I did the harmony test and came back 99% positive for T21 the nuchal translucency measures 4.5. I had the amnio 2 days ago and wating for results.

        • See these two posts here and here. In the second one, the calculator linked in it can show you your actual chance for having a child with Down syndrome (it’s not 99%). You’ll need to enter your age. The fact sheets should be helpful along with the resources on Down syndrome linked in the second post.

  38. Hi Mark,
    I’m due an amneocentisis based on the Quad test I had at 13 weeks pregnant, although I had this in previous 2 pregnancies I just agreed thinking all would be OK. Not the case this time around. My NT came back at 2mm my Papp-a was 0.85 but my beta hcg was super high at 9.22mom which should be only 1, scan was fine. My chances of having a baby with DS are 1 in 87, I’ve tried to get doctors and midwife to elaborate on this for me to understand but it’s like hitting a brick wall. Like they don’t know either. My only answer from the consultant was it is a very complex computer system that works out the odds! How? I am 34 now and have chosen amnio to get answers really as I need to know how to plan ahead. Yet I am an emotional wreck as I know despite the outcome I am putting my baby at risk of miscarriage and that as a mum to be is hard as we do everything we can in pregnancy to keep our babies safe. Having the amnio is like the ultimate betrayal and I’m not in a good place but i need to know. Wish I had never had the test as now I’m on an emotional roller coaster. Just need to know if hormone levels can still be high at 13 weeks? I’m clutching at straws but really dreading the amnio.
    Thanks

    • Unfortunately, I cannot interpret the mystery of screening algorithms either. They are usually proprietary to the lab and therefore are not shared publicly. Amnios are not to be performed before 15 weeks. You may have time before then to request a cell free DNA screening test, like MaterniT21, Harmony, or one available in your locale. Many moms are relying on a screen-negative result from those screening tests as the chance of a false negative is extremely low. With conventional screening, like quad and NT, on the other hand, the chance of a false positive typically exceeds the chance of a screen result being a true positive. In seeking information, you may also find helpful the professionally recommended resources on Down syndrome at this link.

      • Thank you for the reply Mark, I am now 15 weeks + 4 days. I have amnio booked in 2 days time, although don’t know if I will go through with this. I was going to pay for the harmony test privately at £405 as I am in the UK and it is not available on our NHS until 2018. I chose not to do this as I have been informed that it will only come back with a high/low risk and not a definitive answer. I have found this site very useful aswell and I believe my heart will takeover and fears I have in my mind so thank you.

  39. I’m 21 and I already have a 3 yr old who is perfectly healthy with nothing wrong at all. Now pregnant with my second and had the screening test done and it showed positive for DS it says 1:300 is that a low risk?

    • A 1-in-300 chance that your pregnancy is positive for Down syndrome, means you have a 0.3% chance of having a child with Down syndrome and a 99.7% chance that you are not having a child with Down syndrome. Based on just your age, you had around a 1-in-1,400 chance of having a child with Down syndrome. So, your screen result is at a higher chance than just your age-based chance, which would be literally an “increased” chance. However, you can decide if a 0.3% chance is high risk. And, for perspective’s sake, feel free to check out some of the “Our story” posts to see how relatively healthy my daughter, who happens to have Down syndrome, is.

  40. Jessica Scott says:

    I’m 39 and 16 weeks pregnant. I had the blood screening done 12 weeks and 6 days which came back with a 93% risk based on my age and the blood work for Down syndrome. The fluid behind baby’s neck measured at 2.5 mm. There were no other soft markers on the ultrasound. I had two miscarriages prior and no living children. Thus far this has been a wonderful pregnancy with the exception of the normal hormonal changes and an increase in my appetite. Since getting the results this is not sat well with me for obvious reasons. Both my husband and I earn credibly healthy, vibrant. My husband is even two years younger than me.

    We have decided to go to another doctor and get a second opinion as I’ve never met with a doctor but only midwives and a genetic counselor. No one has treated me as high risk from the very beginning and now even with these results no one is talking to us about our questions and concerns. I stumbled across this article in my frantic search about Down syndrome and the likelihood that I’m carrying a child with it. This is been very informative so I thank you for all the information. Based on your knowledge how accurate do you think this blood test is that they’re given me? I will be 40 by the time I deliver which is in September.

    • According to this calculator, the chance that your result is a true positive is 91% and the chance it is a false positive is 9%. I hope the second opinion provides the answers you are seeking. Professional guidelines also recommend that expectant mothers receive informational resources about Down syndrome with a test result. This link is to the one that is most recommended.

  41. Michelle says:

    Hi Mark, I went for my 12 week scan and was told I have 1 in 7 chance of having a baby with a chromosomal abnormality.

    10 week Blood test showed I had ‘low’ levels
    Scan showed that the fluid behind the neck is between 3.6-3.9.
    And they said the blood flowing from the placenta is flowing but it is also flowing back- not sure how to describe it.

    I had cvs two days ago and am waiting for the results.

    Should I prepare myself for the worst?

    Thanks for your help

    • I’m unclear on what they are basing the 1-in-7 chance–was it a cell free DNA screen result or just the NT measurement. If just the NT, that is not recognized by itself as a valid screen. And, even if the 1-in-7 is correct, that would still mean you have an 86% chance that your pregnancy is unaffected, i.e. you have an 86% chance that the screen result is a false positive.

      • Michelle says:

        1/7 was based on my age of 34, blood tests and ultrasound screening.

        They have just called to say that the preliminary CVS screening (taking cells from the placenta) is positive for Downs Syndrome. I have to wait until next week for the final result.

        I can’t believe it! Im devastated!

        • Receiving the diagnosis is often described as a shock and can take time to process. If you would like to learn more about Down syndrome, this link is for the resource recognized by the major professional medical organizations for expectant mothers. Another recommended resource is your local Down syndrome support organization. I hope these are helpful as you process what the diagnosis may mean.

  42. Hello Mark. First of all your article is fantastic and clearly laid out, making it easy to understand so thank you. I’m currently 18 weeks pregnant and at my 12 week scan the doctor said that everything was normal as far as the soft markers are concerned. However the tri test results came back as 1:120 so we proceeded with an NIPT as we didn’t want the risk of the amniocentesis. That test has come back as positive… I will be doing the amnio tomorrow to be certain of course but there is something I don’t understand. Based on my age (32) I have calculated that I have a 34% chance of it being a false positive but the doctor told me that the test was 95% certain. My confusion comes from the fact that his ‘95%’ is neither the 66% that I have just calculated nor is it the ’99+%’ that the test claims to be… Would you know where his 95% comes from? If that makes sense… Thank you for your time.
    Sophie

    • I was curious, too, what your doctor was basing that on, so I entered your revised prevalence rate based off your tri-result of 1:120, expecting that to report a 95% PPV. But, instead, the PPV is only 71%, leaving still a 29% chance of a false positive. So, I don’t know what he’s basing his number on and would be curious what he tells you.

      • Well they said that it meant they were 95% sure that it’s a positive and that the remaining 5% was a margin that they give in case of error like mosaicism etc. Maybe I should have mentioned that I live in France so maybe the tests are different?? I did the amnio today and will have the results on Friday but the ultrasound showed that both brain ventricles are enlarged which does point to trisomy 21…

        • It sounds as though the “95%” figure has no basis except to express that they’re “pretty sure” the test is positive, but it might have a false positive.

  43. Christine says:

    I stumbled upon some of your articles regarding the nipt screening while trying to research the outcome of results that I received. At 13 weeks and 4 days I had an nt scan which returned a measurement of 3.6 and I had the nipt blood test which came back with a positive result for trisomy 21. I am 36 years old and have 2 other children without down syndrome. My doctor tells me the chance of a false positive result on the nipt is .02% that the test is 99.94% accurate as matter of fact the doctor told me the baby has down syndrome without a diagnostic test. The genetic counselor tells me that the results are most likely accurate but I should confirm results with an amnio. Do you think the info I have been provided is accurate. Based on what I read the false negative results seem like they may be slightly higher or am I just reaching for false hope?

    • The information your OB gave you amounts to malpractice. The NT measurement, by itself, is not recognized as a valid screen. Based on your age, your NIPT result actually means you have an 82% chance that it is a true positive and an 18% chance that it is a false positive. (see this calculator here). Feel free to share with your OB the fact sheets on NIPT available at this post or report him or her to your board of medical licensure to prevent further misinformation.

      • Christine says:

        Thanks Mark! I tried to explain to him that I thought he was wrong about the 99.4% but he was not changing his mind. I had an amnio on Thursday and truthfully either way I think now I need a new doctor. Doctors (the person I am trusting with my life and baby’s) should be providing accurate info and not that I wouldn’t still be worried with an 82% chance but a diagnosis before we know for sure has caused lots of anxiety the last 3 weeks that could have been lessened if a different approach was taken.

  44. Michelle says:

    I recieved a High Risk for T21 using harmony blood test. I am 40, had a CVS today found an absent nasal bone and only 1 artery to the unbilical cord instead of 2. Is there any hope my result will come back normal or what percentage would I have.

    Only have my husband for support

    • Based on your age and your Harmony result, you have a 7% chance that it is a false negative. Nasal bone and umbilical arteries are trumped by the Harmony result as far as indicators of T21. You can learn more about T21 from this resource recommended by all major medical organizations.

Trackbacks

  1. […] pregnant with a child with Down syndrome, there is a significant likelihood that the pregnancy will miscarry. There are few published studies establishing those percentages, […]

  2. […] and Down syndrome. When cell-free DNA isn’t (far and away the most-commented-on post) What are the odds that you are having a child with Down syndrome? (easily the most viewed post) Noninvasive prenatal testing for Down syndrome: 99% […]

Leave a Reply

%d bloggers like this: