Levonorgestrel
"I got Mirena about 9 months ago, and am so pleased with it. I am 23 years old and have never had children. The doctor told me this might make insertion more painful, but he decided to try something. He gave me a pill normally used for people with stomach ulcers (sorry, I can't remember the  name of the drug), which had the side effect of softening the cervix. The insertion was not bad at all. It hurt, yes, but not as badly as I've heard from other women who got an IUD before having children. Now, my period is much lighter, my sex life is even better than before because I don't feel worried about pregnancy. Also, it was cost effective. I have health insurance and so it cost about the same amount as 3 months Ortho Tri-cyclen and it's good for 5 years."