Levonorgestrel
"I got Mirena six months ago and I'm so happy that I did.  My doctor did not place Mirena while on my period. I took a pill which softened my cervix and had it placed the next day. There was a horrible pinching feeling when she inserted it, but it immediately stopped once inserted.  I didn't bleed at all until my period started a week later... but then, I bled for three months straight.  It was mostly heavy spotting, but it was inconvenient for three months. Almost to the day, three months later, I stopped bleeding and I haven't had a period since. Getting Mirena was one of the best decisions I've ever made."