How many people have Down syndrome? Last updated 13 Sept 2016

We receive regular enquiries about how many people with Down syndrome live in NSW, or Australia, and about the numbers of births. There are no really reliable current figures on prevalence (the number of people living in NSW at any given time). It is a challenge to calculate, because Down syndrome has only been a notifiable condition (at birth) for about ten years or so, and because we don't have reliable records of deaths. At the same time, life expectancy continues to increase, and has changed rapidly over a couple of generations - that makes the sums hard!


UPDATES

Edit 20 February 2013: 
NSW Mothers and Babies Reports 1996 - 2010 are currently individually linked from this NSW Health web page.

The earliest statistics accumulated are from 1990 (in the 1996 report) - some of the earlier statistics might not be particularly reliable. Notification procedures were improved from 1992. The reports are similar, but every now and again some extra data appears, such as the 2001 statistics which include a breakdown of terminations by the type of prenatal diagnostic procedure.

Edit 20 February 2013: 
National data are collated by the Australian Institute for Health and Welfare, which has published them online and in print from time to time, as Congenital Anomalies reports - but they are currently listed as 'not reported on' (February 2013).

The most recent AIHW data on the birth incidence of Down syndrome is a rate of 11:10,000 given as the rate of Down syndrome occurring among infants at birth 1998 - 2003, in the report, A picture of Australia's children 2009, Part ll: How healthy are Australia's children, p 11 - table of indicators. In Section 7, Congenital Anomalies, Table 7.1 (p 29) gives rates and numbers of babies born with Down syndrome in indigenous and non indigenous populations (no significant difference), and by geographical location with commentary on differences, and notes that termination because of Down syndrome occurred at more than twice the birth rate (25:10,000).

Should you be interested in predicting trends, have a look at the recent Danish study mentioned in this blog entry, reporting a 50% decrease in births with the implementation of a national prenatal screening strategy for all women that had a high uptake rate. We haven't seen that here yet, because we do not have a government funded national strategy for universally offered prenatal screening. In NSW, for example, NSW Health funds nuchal fold screening for public obstetric patients only, who are over 35, or have an "indicative history".

Edit 2/9/2013:
US population prevalence estimates (of the number of people with Down syndrome in the whole US population) have recently been revised down.  The title of Mark Leach's blog post about the new estimate is a little misleading, in that of course it was the previous estimates that were out, not that people with Down syndrome have actually 'gone', as he acknowledges.
GONE: 150,000 fewer people with Down syndrome in the U.S. 
Mark Leach, Down Syndrome Prenatal Testing, 26th August
The estimated number of people living with Down syndrome in the United States has been 400,000. This number has now been reduced by almost 40 percent. The number 400,000 was based on birth estimates: take whatever the birth estimate was, apply it as a percentage to total number of births and total number of lives, and 400,000 was the number that was arrived at. Last month, the Journal of Pediatrics published online a study that revises this estimate based on two key factors. The new study has already resulted in a revision on the Centers for Disease Control website, which lists the highlights.

Edit 29 October 2013:
Down Syndrome Australia has put together the fragmented information that currently exists to provide an evidence based estimate of the number of Australians with Down syndrome.

We believe the population to be over 13,000 and growing. As there is no national, state or territory register of Australians with Down syndrome (with the exception of the IDEA database in Western Australia) this number cannot be rigorously confirmed. However, Down Syndrome Australia is confident that our collation of what little data is available is accurate. You can read the summary here.

Added 8 April 2015:

Estimates of the live births, natural losses, and elective terminations with Down syndrome in the United States

Gert de Graf, Frank Buckley and Brian Skotko, American Journal of Medical Genetics, Vol 167, Issue 4, April 2015
The present and future live birth prevalence of Down syndrome (DS) is of practical importance for planning services and prioritizing research to support people living with the condition. Live birth prevalence is influenced by changes in prenatal screening technologies and policies. To predict the future impact of these changes, a model for estimating the live births of people with DS is required. In this study, we combine diverse and robust datasets with validated estimation techniques to describe the non-selective and live birth prevalence of DS in the United States from 1900–2010. Additionally, for the period 1974–2010, we estimate the impact of DS-related elective pregnancy terminations (following a prenatal diagnosis of DS) on the live births with DS ... Our results and our model provide data on the impact of elective pregnancy terminations on live births with DS and may provide a baseline from which future trends for live births with DS can be estimated.
The full text of this important paper is freely available online here.

Added 13 September 2016:

Study estimates numbers of people with Down syndrome in the US since 1950
Mass General News (Massachusetts General Hospital), 8 September 2016
A new study has estimated, for the first time, the numbers of people with Down syndrome in the U.S., from 1950 until 2010. The total number arrived at by the investigation, which also is the first to break down its findings by ethnic group, is considerably less than previously estimated by several organizations ...

Citation:
Estimation of the number of people with Down syndrome in the United States
Gert de Graaf, Frank Buckley and Brian G. Skotko, Genetics in Medicine (2016). Published online 08 September 2016
  • The abstract is free online, access to the full text of the article requires purchase. 
Down Syndrome Education International (where Frank Buckley is CEO) has published a brief fact sheet distilling the numbers from the new research paper, to answer a series of questions about changes:

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