Anyone waiting until 20 wks for ultrasound?

doeie04

I hear that some women wait until 20 weeks and only have one ultrasound. If you are doing this, do you go in for any other stuff? (To hear the heartbeat, check levels, etc.) I am curious how this works. I think it is a little over the top to have all the ultrasounds if you don't need them (but then how do you know if you don't need them if you don't go in for some sort of testing stuff?)