R.W.
My cousin was conceived on the IUD, and I have heard some other stories as well. I also have the IUD and I LOVE it too, but as with anything there is always a chance. It is supposed to be 99.9% effective with no hormones(I have the copper one, not Mirena). So it is unlikely that you would be pregnant, but babies happen, haha. Anyway this might be a little blunt, but when I know I am probably ovulating we also use the pull out method, just for a little reassurance. Also, it took my body a while to adjust to the IUD. I had some between period spotting and funny periods occasionally, but now everything seems to be working just right. Hope this relieves some of your anxiety.