Low Lying Placenta??

haswelljme

I'm currently 16 weeks, last appointment my ultrasound showed that I have a low lying placenta. OB put me on pelvic rest (no sex, tampons, etc) until my next ultrasound. I had a miscarriage before this, so of course I'm paranoid that something is going to go really wrong...like my placenta will fall out or something. She said most likely my placenta will move to where it is supposed to, but I'm still wondering how this went for other people who had this. 

 Also, should I not be working out? I don't do anything crazy, but I do a pre-natal DVD and elliptical machine. 

 Thanks!