Yes is will. I am 40. Had to terminate when I was carrying a baby with a catastrophic problem a few years ago. The decision was made for me really at that point as it was a hopeless situation and there was only one outcome as the baby was dying.
When I was in the clinic at that awful time, there was a youngish couple - they were in their 30's - and they had been told their child had downs. Now I really felt for them as there decision was far far harder than mine ever could be. I don't know what happened with them. But it does make it real (rather than hypothetical) and made u question what we would have done (which we did, at length)
In all honesty, I don't think I could have gone through with the pregnancy really, had I been them. Call it cowardly or mean or whatever. But there it is.
But everyone is different. I admire those who would go through with it regardless in the case of something like Downs. But I know I am not that person.
The downs tests are VERY ambiguous though. All people really want is a straight answer and the tests simply can't give you that. We look to our doctors and midwives for guidance they cannot and will not give on questions like "what should I do". Its all about percentages and what not and its not great. A necessary good or evil, depending on how you look at it.