Thoughts on chromosomal testing

I went in for a second appointment and US earlier this week and everything looks good. The doctor kind of surprised me and asked me back in five weeks for some chromosomal testing to screen for Down Syndrome and other abnormalities. Is this pretty standard practice? I hadn't really thought about it before and it got me thinking and weighing my options. I understand the benefits of knowing but am curious if others are having this done as well. Does insurance usually cover such a test?