A friend of my daughter has just had the same test and it has come back that she has a 1 in 19 chance of having a down syndrome baby.
I thought this was quite high.

Then I saw on the front page of the Guardian on Saturday there was an article on this very subject. It turns out that many test are wrong and they are putting parents to be through so much worry. I didn't read the whole piece but they did say that further tests such as the Amnio tests are more accurate.
Maybe you could find the article on the newspapers website.

Hope all is well and good luck.

Woodentop