I don't think an amnio would have set my mind at ease. I'm convinced my LO started out perfect based on the tests they were able to do, and just looking at his U/S pictures. What worries me is after all that...as the pregnancy progresses and even during the birth, and I think about silly things like squishing him or his hiccups and cord compression and all the multitude of things that can cause brain damage, etc.
Basically, my worry cannot be alleviated by anything on the outside. I'm just going to worry anyway.
Today my new worry is a swollen ankle and sudden weight gain. So, got a call in to my doctor to see if I should be concerned with that. If it's not one thing, it's something else.