Okay so I got a paragard (copper) iud between my first and second pregnancy. I took it out after 1 year to have baby #2. after that baby I got the same iud. now 25 months later I am 8 weeks pregnant. my iud expelled itself. I guess on a heavy period, my periods have been heavy!!!!! I never checked strings I thought it was too weird, I was spooked and didn't want to hurt myself or pull it out by accident. now I cant even tell you when it fell out either, could have been a while, I didn't feel It. but check your strings ladies. lol