Is Down Syndrome Disappearing? Well, Not Exactly But….

Iceland has given the world the Eddas, Sigur Rós, Björk, and some magnificent geology.  A more ambiguous achievement, though, is suggested by a recent CBS News story that claimed that Down syndrome is disappearing from Iceland as a result of prenatal testing. The claim has been bouncing around the Internet for a few years. The earliest reference I could find was a November, 2015 letter sent to the Office of The United Nations High Commissioner for Human Rights authored by Downpride, an international advocacy group for people with Down syndrome. The letter is an “[a]ppeal to the United Nations to stop discriminatory use of prenatal genetic screening aimed at eradication of people with Down syndrome and other groups.” It was, in my view, an understandable and justifiable reaction to largely non-critical widespread adoption of Noninvasive Prenatal Testing (NIPT) from a community that has good reason to be concerned. Needless to say, it generated a lot of heated reaction. Just Google “Iceland Down syndrome” and you will see what I mean.

Delving into the story was like getting lost in a hall of mirrors; many sites simply referenced each other. But the claim that Down syndrome is disappearing from Iceland and that 100% of pregnancies with Down syndrome in Iceland are terminated turns out to be not quite so straight-forward. While Iceland represents a microcosm of the larger concerns of people with disabilities, their families, and their supporters, it is not necessarily an accurate reflection of the macrocosm of the larger population dynamics of Down syndrome in other countries, particularly the United States.

The ultimate source of the data, according to the Downpride letter, was testimony presented to The Althing, the Icelandic parliament that is the world’s longest existing legislative body. I tried unsuccessfully to find that testimony. I then searched PubMed but found only limited help. So I decided to do my own back-of-the-napkin calculations. I obtained the birth distribution by maternal age in Iceland for 2016, and grouped the ages by quinquennia. The expected frequency of Down syndrome was based on data from 1976, prior to the advent of widespread prenatal diagnosis.

Age Group # of Births Exp. Frequency of Down S. Exp. # of births with Down S.
15-19 72 1/1667 0
20-24 592 1/1587 0.37
25-29 1305 1/1087 1.2
30-34 1218 1/763 1.6
35-39 672 1/248 2.7
40-44 165 1/79 2
45+ 10 1/24 0.4
Total 4034  1/488 8.27

 

Thus, in Iceland in 2016, there were 4034 births. In the absence of prenatal diagnosis and selective termination, 8 or 9 babies with Down syndrome would be born, for a frequency of ~1/450-500 births. I then made the following assumptions, acknowledging that each has some potential error:

  • Based on a 2016 publication, about 80% of pregnant Icelandic women will choose to undergo prenatal screening
  • According to Dr. Hulda Hjartardóttir, chief of obstetrics at Iceland’s National University Hospital, among Icelandic woman who have a positive screen, about 25% decline diagnostic testing and continue the pregnancy. Thus, roughly 1/3 of Icelandic pregnant women either do not undergo screening to begin with or decide to continue the pregnancy and not proceed to diagnostic testing if a screening test is positive. The impact of these percentages on Down syndrome frequency depends on the age distribution of those who declined screening or diagnostic testing, but for argument’s sake, I assumed an equal distribution across maternal ages.
  • 100% of women whose pregnancies are diagnosed with Down syndrome will choose to terminate. I could not verify this claim, but I decided to go with the most extreme scenario. This has not been the experience in many countries, where termination rates have been high but not typically 100%.
  • The CBS News story mentions the Combined Screen, so I assumed this was the standard screening test in Iceland when the claims were made in The Althing. I therefore set the detection rate for Down syndrome to 90%, that is, of all women undergoing screening, about 10% of pregnancies with Down syndrome will be screen normal and would not proceed to termination (some studies suggest that the Combined Screen may have a sensitivity somewhat less than 90% but because about 21% of pregnancies in Iceland occur in women 35 and older, a higher sensitivity – and false positive – rate is expected).

Based on these assumptions and the above table, of the potential 8-9 babies born with Down syndrome, about 2-3 would actually be born because their mothers did not undergo either prenatal screening or diagnostic testing, and another baby with Down syndrome would be born because the Combined Screen would be expected to miss about one case. In other words, the total number of newborns with Down syndrome in Iceland would be expected to drop from 8-9 every year to about 3, maybe 4, per year. These numbers could increase or decrease with many factors, such as changes in fertility rates, maternal age distribution, the sensitivity of screening tests, social trends that influence the choice of abortion, and random fluctuations that occur with any demographic trend especially with the small number of births in Iceland (about that many babies were born last year in the hospital where I work in Seattle). If readers know of empirical data from Iceland to support or refute my estimates, please share it.

Of course, for advocates, every loss of a pregnancy with Down syndrome is serious, no matter how small the number. But these estimates put the concerns in some perspective. Among other things, it is fair to say that most, but not 100%, of pregnancies with Down syndrome are terminated in Iceland, and the birth prevalence of Down syndrome in Iceland is falling considerably but not likely, in my view, to disappear entirely.

I think a more realistic picture of the impact of prenatal screening on Down syndrome, in the US at least, is provided by Brian Skotko and his colleagues Frank Buckley, Jennifer Dever, and Gert de Graaf in a recent publication in the American Journal of Medical Genetics. Over the last few years, they have consistently provided some of the most reliable estimates of the demographics of Down syndrome and the effects of prenatal screening.

According to the de Graaf et al. paper, a detailed look at changes over time in the demographics of Down syndrome in 9 states, the number of people living with Down syndrome has steadily increased since 1950. The two major factors driving that growth have been longer survival due to better medical care along with the unrelenting trend of the last 35-40 years of delayed childbearing. This growth, however, has been partially offset by a loss of births with Down syndrome due to prenatal screening. The loss varies with geographic region, but overall, the prevalence of Down syndrome is roughly 70% of what it would be if prenatal screening were not available. Interestingly, the most growth in the Down syndrome population occurred among Hispanics and Native Americans. So, unlike the near elimination of Tay-Sachs disease in many Ashkenazi Jewish communities, the prevalence of Down syndrome is dropping, but not close to disappearing, at least in the US.

Other factors may affect the Down syndrome birth frequency, such as changes in maternal age distribution, availability of abortion, and access to health insurance. For example, in the highly unlikely event that every woman 35 and older refrained from pregnancy, the birth frequency of Down syndrome in the US and many Western European countries would be reduced by more than 50%. On the other hand, if abortion were to become illegal (not highly unlikely), then presumably the birth frequency of Down syndrome would increase. Limiting access to good medical care (unfortunately also not highly unlikely in the US) could lower the overall prevalence of Down syndrome because of reduced survival.

Current trends suggest that, for the immediate future, prenatal screening will continue to reduce the birth prevalence of Down syndrome. It is becoming increasingly easier for women to undergo prenatal screening and more difficult to just say no. This is due to aggressive marketing by commercial labs of “newer, better, bigger, cheaper” screening tests like NIPT; the dearth of time and resources devoted to unbiased education about Down syndrome and the pros and cons of screening tests; inequitable social distribution of medical resources and social support; and the rarity of long, difficult discussions between pregnant women/couples and their providers about whether they should even enter the prenatal screening cascade to begin with. It also does not help matters that the current US President lacks any moral decency and takes pleasure in mocking people with disabilities.

Although I am a strong supporter of women’s reproductive rights and well-informed, gut-wrenching decisions to terminate a pregnancy, it is becoming increasingly difficult to provide ethical justification for further expansion of prenatal screening, or expanded carrier screening for that matter. This is something that society needs to address but particularly genetic counselors because we are in the thick of it.

As I have previously argued, almost no research has been conducted that has tried to demonstrate whether prenatal screening can improve the medical, social, and emotional lives of people with disabilities and their families. Some women undergo prenatal screening because they think it will prepare them for raising a child with Down syndrome, but we really can’t tell them if screening does help or if it is worth their emotional and psychological investment. Carrying out such research is critical. If we can demonstrate broader benefit of prenatal screening, then we can open up a dialogue with the disability community rather than continue the shouting matches, and offer greater and more equitable justification for NIPT and other screening technologies.

Or we can continue shouting at or dismissing one another.

 

10 Comments

Filed under Robert Resta

10 responses to “Is Down Syndrome Disappearing? Well, Not Exactly But….

  1. Rob, I have known who you are (we’ve actually met- I used to work with Ed Kloza) and I’ve respected you and enjoy your blog. I was excited to open this and see your break down of this recent discussion and I was going to share it. Then- I came to the part about the president. You took your credibility and dumped it down the drain. Firstly, a great friend of mine has a child with a disability and researched the whole situation that led to the media claims that Trump mocked that reporter with a disability. She and many others are not convinced that it was as reported. Let’s just say that it was – after all of your years as a prenatal counselor – you actually believe that this last 7 months of this presidency actually is affecting the choices women make about terminating a pregnancy with Down Syndrome? Your blog opened up as a beautiful scholarly discussion and then turned unnecessarily political. I’m disappointed that a brilliant mind with intelligent things to share had to go there when it was completely unecessary.

    • Robert Resta

      Renee

      Thanks for your thoughtful reply. You raise some very good points. What I love about the readers of this blog is the wide range of opinions and viewpoints of the readers. I hate being in an echo chamber. I like being made uncomfortable and forced to continually examine my own views and assumptions.

      I thought long and hard about including the political comment before I added it. I also understand the questions that have been raised about the meaning of the then presidential candidate’s purported mocking of the reporter. In fact, as you may know, the president has used the same technique of arm contortions and speech stumbling to depict people who did not have visible disabilities, including military leaders. But I guess we all see in our leaders what we want to see; I am not free of bias.

      The problems I have with this type of reaction is that, whether or not it is a caricature of a specific person, it strikes me that it is a stereotypic depiction of somebody who has cerebral palsy (as I understand it, the NY Times reported has arthrogryposis, not cerebral palsy). So, in my view, the President was mocking people with disabilities in general on several occasions, not necessarily the specific disabilities of that reporter on that one occasion. In fact, Ann Coulter, one of the President’s staunchest defenders, justified his depiction as a “standard retard” rather than a depiction of the specific reporter, so I am not the only one who thought that he was offering a caricature of people with disabilities.

      So why is this relevant to my blog post? I did not mean to suggest that individual women’s decisions stem directly from the President’s comments. But the President’s business properties have a long history of fighting lawsuits that try to gain access for people with disabilities. In addition, the budget he proposed back in May would disproportionately negatively affect people with all kinds of disabilities, genetic, congenital, or otherwise. So these factors can affect the social acceptance of people with disabilities and the resources allocated to them, as well as indirectly influencing attitudes toward disability. As I said in the posting, it does not help the situation (though of course in and of itself does not determine it). But it does not help set a welcoming and accepting embrace of the wide range of human variability, which I think the Clinton, Bush, and Obama administrations at least strived for. As such, we should criticize it.

      In addition, the President helps set – but of course does not determine – the moral tone of the country, which in my view, should be one of broad acceptance and support. The disability community fought long and hard to get the ADA passed, and we should all be leary of any trends that try to directly or indirectly limit those achievements.

      But I hope that I am wrong and the President and the country will make it clearer that everyone isl an equally important part of the American social fabric. And I am glad that the genetic counseling community includes a diversity of opinions besides mine.

      Bob

      • Bob,
        Thank you for that thoughtful reply. You see – I didn’t vote for him as you may have assumed from my response. I am exhausted by everything political and exhausted by the constant blaming of him for the ills of our society. I had more faith in “us”/humanity than that and sadly have lost much of it. When I opened your post to read about this topic, maybe I was also assuming that by choosing to read something scientific and in my area of interest I might be able to escape the barrage of political commentary on either side about every topic imagineable (even the solar eclipse!). Thank you for clarifying that you didn’t mean to insinuate that a woman’s agonizing decision would be affected by the President’s comments. That was upsetting to me as I don’t believe that in all of my experience that anything that shallow had ever come into play in the decisions of any of the women I’ve counseled or known. That would further decrease my faith in humanity, if that is even possible at this time. Again, thank you for your thoughtful response.

  2. Vivien

    Its obvious that Renee did not see the two events (I did) when Trump mocked two different reporters with disabilities but listened to the comments from her friends. The media reported this issue correctly but Trump’s insistence that its ‘Fake news’ is always used by Trump to cover up his negative behavior. We all need to see beyond this and seek the truth. I also saw the presentation regarding the eradication of Down syndrome in Finland and was surprised by it because of the limitations in NIPS and that women can choose to not have prenatal screening allowing nature to take its course. All Bob did was to present a very well written and researched article which did address issues that need to be considered. I applaud him for his efforts.

    • Like I said – fake news or not – it wasn’t necessary in this otherwise well written post. Why everything in this country has to be made political is beyond me – especially in situations when it is not relevant – I thought “we” were above that.

      • Shannon

        I think the politics and the current political climate is relevant–especially the fight over healthcare going on in Congress and influenced by this president. I know many parents of children with a wide range of health concerns that were very involved in that battle, given their children’s future insurability and the cuts to the Medicaid that many of these individuals rely on through childhood and adulthood. So, I think that the ability to raise a child with any health concern is affected by our nation’s lack of affordable access to health care and health insurance. I support a single payer system. Imagine if families who faced prenatal diagnoses of Down syndrome or anything else were able to face their decisions without the baggage of worrying about how they will pay the hospital bills. I know from even my limited prenatal counseling experience that this would be a factor in some decisions.

      • Shannon – I never said that a discussion of the healthcare system was irrelevant – rather the sentence about the President’s comments/actions. In my 16 years of prenatal counseling and my experience with support groups for women who have terminated their pregnancies due to Down syndrome or other conditions and my personal relationships with women in the 11 years since leaving prenatal counseling – I have never met a woman who terminated her pregnancy based on a comment by the likes of someone like the president. The comment was unnecessary and irrelevant. If it comes down to that, then none of us are doing a good job and should take a darn good look at our profession and society as a whole.

      • Andrea

        I see what you are saying, Renee, about someone not making a decision based on specific comments made by the President. However, I think the point that was being made is that comments and actions such as that can contribute to the societal view of disability. While that specific action may not directly affect a woman’s decision to terminate a pregnancy, societal views of disability may. Whether we like it or not, we are all influenced in some way by societal and cultural norms.

      • Andrea, I completely understand what Bob was trying to say and if it were said that way I would never have reacted to the sentence in the way that I did. The way things are phrased, the words we say – we as professionals should be more careful. How can we expect our children and others to if we can’t? Until that sentence the article was scholarly. We are above that. Or at least I would like to think we are.

  3. Hi Bob,

    Thank you for your thoughtful post. Our current political climate notwithstanding, the ‘Iceland’ article was an interesting piece of publicity for our profession that is still foreign to so many.

    Like many folks, I felt rather uneasy reading the article. My first thought was that perhaps the “counseling” was less-than balanced and that Icelanders had a very different cultural view of disability. But I’m not entirely sure. Could this just be the natural sequelae of widespread prenatal screening? Where screening is becoming earlier and more advanced, could it be that the process becomes so routinized that the future “decisions” are implicit and seemingly pre-determined?

    I agree with your statement that more research needs to be done on the potential “benefits” of prenatal screening for preparing for a future pregnancy. I remember one paper recently that reviewed the possible health benefits of screening for Klinefelter syndrome prenatally in order to start early hormonal treatment; the authors somewhat glanced over the figure that up to 70% of XXY fetuses are terminated. At some point we have to be sure we aren’t just kidding ourselves with the “other” reasons for prenatal testing.

    Ultimately, I do think the United States has a very different culture than Iceland and that we are unlikely to find ourselves in a the same situation (I saw many Facebook posts sharing the CBS article with comments such as “terrible!” and “all life is precious”). I’m still left wondering, though, how is this all going to look in 10 years?

    Mike

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