I wouldn't even consider starting a family later than 35. And look at 45! More than a 1 in 33 chance you will have a child with Down syndrome (Trisomy 21) after 45...those are definitely not gambling odds.
Those numbers are far too small to base such a life changing decision on.
And this kind of risk to the baby is not nearly as serious as a risk to the mother. You can always try again. These are the stats you should be considering.
http://en.wikipedia.org/wiki/Image:Trisomy21_graph.jpg
I wouldn't even consider starting a family later than 35. And look at 45! More than a 1 in 33 chance you will have a child with Down syndrome (Trisomy 21) after 45...those are definitely not gambling odds.