Hi,
I always thought I would have an amnio no matter what as am somewhat older at 44 (43 when I conceived); but our NT/bloods lowered our risk from 1/27 to 1/162 to downs and 1/40 overall to 1/955 to others; my 20wk scan lowered it to 1/300 as the heart and all other soft markers are good. We decided that with the risk of m/c at 1/200 and my overall blood/NT risk about even, not to do an amnio. We were a month or so away from possible IVF, so consider this little one a bit of a miracle and are cautiously hopeful. I know here in Ireland, it is considered routine over 40, and have read that under the NHS, under 40, there has to be a reason, e.g. high risk blood work, so they may require you to do the NT/bloods anyway. We're private here in Ireland as had a terrible public hospital experience when having a m/c two years ago.
best wishes