I am not sure about the original question. I have never heard of anyone that does not advocate things like reccomending folic acid to women. It is in fact reccomended to women of childbearing age routinly, even if they don’t plan to become pregnant.
I don’t know about the US, but here common foods like flour are routinly fortified with folic acid, just like salk is routinly iodized. People take this quite seriously.
I think the reasons stats for abortion of DS babies are going up is complex, and not really all about pro-choice vs pro-life. Part of it is that tests for DS are more readily available. As well, it used to be that they were only recommended to higher risk people. But because numerous people have sued doctors after having a DS baby and not being offered the tests, they tend to be offered to all. If it isn’t, the insurance company will not support the doctor, and esp in the US, the insurance companies are the ones who really decide health policy, based on money issues.
As well, I think there is a psychological issue. In my province, the recommendation for receiving the genetic testing has recently changed, so that there is a positive recommendation that all get it. (Before, it was available but only recommended for specific situations.) It tests only for DS and spina bifida and related problems.
But most people do not know much about any of these, and they rather assume that if they are being told it is best to test for them, they must be really terrible. And of course many do the testing simply because it is recommended, like many other prenatal procedures. Then they are left with the results and must figure out what to do with them.
So it feeds off itself - because it is recommended (based on monetary/legal considerations), people assume it is important and necessary. Tfey become more and more afraid of not getting the tests, or what to do about them. And knowledge of the real meaning of these disorders becomes less and less because it is seen less and less.