The latest Annual Report from the National Down Syndrome Cytogenetic Register (NDSCR) has been published. NDSCR collects data on babies diagnosed with Down syndrome throughout England and Wales. The Annual Report provides updated data for 1998 through to 2011, though the 2011 numbers remain provisional.
In the five years from 2006 to 2010, an average of 741 babies were born with Down syndrome each year in England and Wales. Extrapolating on the basis of population, we can estimate that an average of 836 babies were born with Down syndrome each year from 2006 to 2010 in the United Kingdom. There were 16% more babies born during this period than the previous five years (2001-2005) and 19% more than in the five years prior to that (1996-2000). In other words, there are around 19% more babies being born in England and Wales than 10 years ago.
Of course, some of this increase is due to an increase in births in general. In the five years from 2006 to 2010, the live birth prevalence of Down syndrome in England and Wales averaged 10.6 per 10,000 (1 in 944 babies). Live birth prevalence was during this period was 3% higher than in the previous five years (2001-2005: 10.3 per 10,000) and 8% higher than in the period prior to that (1996-2000: 9.8 per 10,000). In other words, the live birth rate in England and Wales is 8% higher than 10 years ago.
The recent increases in live births and live birth prevalence (babies born with Down syndrome as a proportion of all babies born) seem to have peaked in 2009 with 774 births in England and Wales (1.1 per 1,000 or 1 in 912 live births) and fallen to around 725 annual births (1.0 per 1,000) in 2010/11.
There seems to be a slight trend towards fewer terminations being chosen after a prenatal diagnosis – from around 92% in the late 1990s to around 90.5% in recent years. Note that this is the proportion of babies prenatally diagnosed with Down syndrome that were terminated – not the proportion of all babies with Down syndrome.
Babies with Down syndrome (and other trisomies) are substantially more likely to be lost during pregnancy than other babies. Therefore, the number of terminations recorded does not tell us how many babies were not born that would have been born in the absence of genetic screening and selective terminations. This is because many of the babies terminated would not have survived to term in the absence of intervention.
In 2010, there were 1,111 terminations recorded. We can estimate (from the ages at which mothers gave birth in that year) that 1,613 babies would be expected to be born with Down syndrome. Therefore, 888 (55%) fewer babies with Down syndrome were born in 2010 than would have been born in the absence of genetic screening and selective terminations.
Given recent trends in births, we can estimate that there are approximately 37,000 people with Down syndrome living in the United Kingdom today.