Ben Goldacre

The Guardian

Saturday November 29 2008

As usual, it’s not Watergate, it’s just slightly irritating. “Down’s births increase in a caring Britain”, said the Times: “More babies are being born with Down’s syndrome as parents feel increasingly that society is a more welcoming place for children with the condition.” That’s beautiful. “More mothers are choosing to keep their babies when diagnosed with Down’s Syndrome” said the Mail. “Parents appear to be more willing to bring a child with Down’s syndrome into the world because British society has become increasingly accepting of the genetic abnormality” said the Independent. “Children’s quality of life is better and acceptance has risen”, said The Mirror.

Their quoted source was no less impeccable than a BBC Radio 4 documentary presented by Felicity Finch (her what plays Ruth Archer), broadcast on Monday. “The number of babies with down syndrome has steadly fallen, that is until today, when for the first time ever that number is higher than before, when testing was introduced.” I see. “I’m keen to find out why more parents are making this decision.” They’re not. “I was so intrigued by these figures that I’ve been following some parents to find out what lies behind their choice.” Felicity. Wait a second. The entire founding premise of your entire 27 minute documentary is wrong.

There has indeed been a 4% increase in Down’s syndrome live births in England and Wales from 1989 to 2006 (717 and 749 affected births in the two years respectively). However, since 1989 there has also been a far greater increase in the number of Down syndrome foetuses created in the first place, because people are getting pregnant much later in life.

What causes Down syndrome? We don’t really know, but maternal age is the only well-recognised association. Your risk of a Down syndrome pregnancy below the age of 25 is about 1 in 1600. This rises to about 1 in 340 at 35, and 1 in 40 at the age of 43. In 1989 6% of pregnant women were over 35 years of age. By 2006 it was 15%.

The National Down Syndrome Cytogenetic Register holds probably the largest single dataset on Down syndrome, with over 17,000 anonymous records collected since 1989, and one of the most reliable resources in the search for patterns and possible causal factors. They have calculated that if you account for the increase in the age at which people are becoming pregnant, the number of Down’s Syndrome live births in the UK would have increased from 1989 to 2006: not by 4%, but from 717 to an estimated 1454, if screening and subsequent terminations had not been available.

Except, of course, antenatal screening is widely available, it is widely taken up, and contrary to what every newspaper told you this week, it is widely acted upon. More than 9 out of ten women who have an antenatal diagnosis of Down’s syndrome decide to have a termination of the pregnancy. This proportion has not changed since 1989. This is the “decisions” that Felicity Finch, Radio 4, the Mail, the Times, the Mirror, and the rest are claiming more parents are taking: to carry on with a Down syndrome pregnancy. This is what they are taking as evidence of a more caring society. But the figure has not changed.

Crass and insensitive moral reasoning helps nobody. If I terminate a Down syndrome pregnancy, is that proof that society is not a warm caring place, and that I am not a warm caring person? For many parents the decision to terminate will be a difficult and upsetting one, especially later in life, and stories like this make a pretty challenging backdrop for making it. This would have been true even if their figures had been correct, but as is so often the case, for those with spare flesh to wave at strangers, their facts and figures are simply incorrect.

The National Down Syndrome Cytogenetic Register felt obliged to issue a thorough clarification. The thoroughly brilliant “Behind the Headlines” service on the NHS Choices website took the story to pieces, as they so often do, in their daily round up of the real evidence behind the health news (disclosure: I had a trivially tiny hand in helping to set this service up).

Everybody ignored them, nobody has clarified, and “Born With Down’s” remains Radio 4’s “Choice of the Day” on the Radio 4 website.

Please send your bad science to ben@badscience.net