How many babies with Down syndrome are currently born each year in the United Kingdom?

I am not sure why, but the figure most often quoted for the number of babies with Down syndrome born each year recently in the UK is 750. I am guessing this figure is drawn on data published the National Down Syndrome Cytogentic Register.  However, this is does not cover the whole of the UK – only England and Wales.

England and Wales is fortunate to have a registry recording the births of babies with Down syndrome. It has reported live births, prenatal diagnoses and pregnancy outcomes since 1989 with a high degree of accuracy. In fact, it offers probably one of the most useful datasets available anywhere in the world.

Rather irritatingly, the work of NDSCR has recently been transferred the National Congenital Anomaly and Rare Disease Registration Service (NCARDRS) and the Congenital Anomaly Register and Information Service (CARIS) for Wales. The move around means no data for 2014 or 2015 has been published for England. I am told it will be next year before this appears. CARIS only appears to be reporting total cases, which is unhelpful. Hopefully, the NCARDRS and CARIS will pool their data to continue to publish the England and Wales data series.

Scotland reports live births back to 1991, though apparently not prenatal diagnoses and pregnancy outcomes. Northern Ireland does not seem to publish data on live births of babies with Down syndrome.

Drawing on these data sources, we can compile a total for UK live births going back to 1991:

figure-births-babies-down-syndrome-uk-england-wales-scotland-northern-ireland-1991-2015

As Northern Ireland does not seem to publish a count of live births of babies with Down syndrome, I have estimated them by taking published data on all live births broken down by age of mother and multiplying these by the formula expressing the maternal-age-related chance of having a baby with Down syndrome (to get the expected number of ‘natural’ live births in the absence of selective terminations). I have then reduced this number at the same rate as ‘natural’ live births have been reduced by terminations in each year in England and Wales. To estimate births in 2014 and 2015 for England and Wales, and for 2012-15 for Scotland I have again calculated the expected ‘natural’ live births and reduced by the recent average reduction rates in each area. (Of course, the reduction rates may have risen in the past few years with the private availability of NIPT, but we do not have the data yet to see this.)

Given these assumptions, we can calculate that the average annual live births of babies with Down syndrome in the United Kingdom over the past 5 years is 847.

Year England and Wales Scotland Northern Ireland UK 5-year UK average
1991 737 75 29 841
1992 663 65 25 753
1993 621 60 23 704
1994 639 64 24 727
1995 581 73 21 675 740
1996 607 62 22 691 710
1997 667 88 24 779 715
1998 633 60 23 716 718
1999 604 63 21 688 710
2000 594 64 20 678 710
2001 580 54 20 654 703
2002 589 36 20 645 676
2003 616 51 20 687 671
2004 665 68 22 755 684
2005 747 64 24 835 715
2006 764 53 25 842 753
2007 723 70 24 817 787
2008 754 61 26 841 818
2009 793 76 26 895 846
2010 737 53 25 815 842
2011 758 61 25 844 842
2012 779 63 26 867 853
2013 728 62 24 814 847
2014 759 64 25 848 838
2015 774 62 26 861 847

As ever, I must acknowledge helpful discussions about the data with my colleague Gert de Graaf. As soon as we can get the most recent data I hope we will publish a larger historical births and populations dataset. However, any errors are all mine!

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