I had the Mirena IUD inserted at my 6 week check up after having my second daughter (who I got pregnant with while on the patch by the way). The day i got it put in I had really bad cramps and thought there was no way I was going to be able to keep it in but the next day I woke up and didn't feel a thing. I haven't had any weird or severe side effects that I have noticed and my daughter is about to turn 3 in a couple weeks. My periods do seem to come more frequently, about every two and a half to three weeks, but they are very light and only last couple days. I've found that it is very difficult for me to lose weight on birth control in general but I haven't experienced any weight gain on Mirena (as opposed to the 50 pounds I gained in the 4 months I was on the depo shot after my first daughter!). All in all I would have to say that the Mirena has been the best birth control method that I have tried so far. I am considering having it removed next year but only because we're thinking about having one more baby.