I've had a Mirena IUD in since fall 2006. It was a godsend because prior to that I'd always had really, really heavy periods. After getting the Mirena, getting my period was a lot like spotting, and I could get away with panty liners during it. It would also last 3-5 days instead of 7. Now, however, having switched to a much more paleo diet, it's getting heavier (but still nowhere near what it was like pre-Mirena) and lasting 7-9 days. I think it's also coming closer together, but I haven't been organized enough to track it.