I had 3 in my late 30s after smoking for decades and all three are just fine, actually better than fine.
While age definitely plays a factor, beyond that I really think it’s a roll of the dice. Sarah Palin leads a healthy lifestyle and had a Downs Syndrome baby she considers not only ok, but a blessing to her family. Nobody prays for their child to be born with Downs Syndrome, but mature couples who have faith certainly can accept it and see the blessing. What the Sarkozy’s would do is anyone’s guess.
I've read there's a big difference between late 30’s (like you) and mid 40’s (like SP) in regards to developmental problems and having kids.
OTOH, I had a neighbor back when I was growing up that was a heavy drug user (coke, grass, glue sniffing, who knows what else) and she had a daughter at 17 that is so severely retarded (wheelchair-bound, cannot speak, etc), we used to say the skank mother should have been arrested for child abuse and/or attempted murder.
Good luck to the Sarkozys.