Down's births: how BBC misread the evidence

[Guest guest]

Down's births: how BBC misread the evidence

Comments

(4)

Ben Goldacre

guardian.co.uk, Saturday November 29

2008 00.01 GMT

The Guardian, Saturday

November 29 2008

Article history

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 Monday. " 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.

http://www.guardian.co.uk/commentisfree/2008/nov/29/downs-syndrome-bbc