Now, if you find the statistics for Down’s children born to a 20-year-old, that might be relevant.
Um, are you having reading comprehension problems? Bad case of the Mondays?
I wrote (in the post you responded to):
Maternal age influences the chances of conceiving a baby with Down syndrome. At maternal age 20 to 24, the probability is one in 1562
It's right there, in black and white. A 20 year old has a 1:1562 chance of conceiving a Down Syndrome baby.
There was absolutely no need for you to take an insulting tone. If you wanted a different piece of information, or clarification, you could have asked nicely.