We had our monthly visit with the doc yesterday - officially at 21 weeks! Turns out she is a little more concerned about the placenta previa than the ultrasound doc was. She's upped my visits to every two weeks instead of monthly, and I have orders that if any bleeding or spotting occurs I am to call immediately. I guess there is a risk the placenta will rupture and I will start hemorrhaging - with is very bad for both of us. There are no warning signs or symptoms, and not much can be to to reduce the risk except the passage of time.
From what I've read, it's fairly common, but becomes more of an issue in 1) smokers (which I am not) and 2) older mothers (which - biologically anyway - I am)
We'll have another complete fetal survey at 28-30 weeks to see if the placenta has moved. If not, we start planning for a C-section because a natural birth will be impossible.
On the bright side, Little One's movements are becoming stronger, more pronounced and more frequent. I'm pretty sure s/he's swimming laps in there. :) The doc had a hard time keeping the heartbeat going on the doppler yesterday because s/he'd squirm away as soon as we found it. Stinker :)