cece - first congratulations on your pg! I remember discussing wanting another baby on another thread that you were on - I had no idea you were pg now! - v happy for you. (And still hopeful for myself )
Now re the Downs risk - I had a similar call - though longer odds more like 1:150, but still scary, mainly becasue of the immense pressure I was put under to have an amnio and the way the midwives cted as if it was a terrible disaster (one actually came round to the house with a face like thunder to give us the news - DP and I were trembling and holding hands thinking she was going to say the pregnancy wasn't viable - when she said there's a high risk of Downs I could have slapped her - it's not that terrible!).
Firstly their definition of high risk isn't that high - 50:1 is crap odds on a horse for example. There is still essentially a low risk.
Secondly think about your dates. The result of these tests is affected by when in the pg they are taken. My own dates for conception and due date were at least a week out from what I was told at the booking scan (and I knew when I conceived). The downs test results were based on their dates. I asked if them being a week out could afect the result and they said yes, it would make a "high-risk" result more likely. Remember these tests are just a guide, not always accurate.
Lastly the wise words of Thomcat, Eidsvold and others on here have helped me to see that a child with DS is every bit as much a blessing as any child and (some possible health issues notwithstanding) generally not the disaster that so many health professionals seem to make out (why they do, I have no idea).
In the event, I too strongly felt I did not want further tests, especially any that could risk the pregnancy, and said no (which was bloody difficult I can tell you - the midwife actually made me an appointment at the hospital, when we went in we realised it was for the actual amnio and the machine was right there, there were 3 staff trying to talk me into it, I cried a lot and when I insisted no, they all seemed disappointed). Instead I chose to read up on DS just in case, and by the time of the birth I felt OK with the possibility. DS was born healthy and without Downs btw.
Good luck Cece. It's your body and your pregnancy and you should decide - do what feels right.