The Guardian disputes BBC information about Down syndrome birth rates in Britain

From the Bad Science column by Ben Goldacre in The Guardian Nov. 29:

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.

Their quoted source was a BBC Radio 4 documentary presented by Felicity Finch (her what plays Ruth Archer), broadcast on Nov. 24. "The number of babies with Down's syndrome has steadily 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 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's syndrome foetuses created in the first place, because people are getting pregnant much later in life. Risk of a Down's syndrome pregnancy below the age of 25 is about 1 in 1,600. 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's syndrome. 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 1,454, 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 nine out of 10 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. For many parents the decision to terminate will be a difficult and upsetting one, especially later in life, and stories like this create a pretty challenging backdrop for making it.

The National Down Syndrome Cytogenetic Register felt obliged to issue a thorough clarification. The brilliant Behind the Headlines service on the NHS Choices website took the story to pieces in its daily roundup of the real evidence behind the health news (disclosure: I had a tiny hand in helping to set this service up). Everybody ignored them, nobody has clarified, and Born With Down's remains Choice of the Day on the Radio 4 website.