I had Mirena inserted a little over a month ago. This cycle I had A LOT of unprotected sex, especially when I was ovulating. I'm supposed to get my period in a week and I just realized I have brownish discharge in my underwear. I'm afraid this could be implantation bleeding, which I read happens about 6-12 days after conception so it's around the time it would happen.. How likely is it that I have become pregnant on Mirena?? Has this happened to anybody? If it's not implantation bleeding, what could the brownish discharge be?