Levonorgestrel
"I've had Skyla for a little over a year now. For the most part, I love it...But, yes there's a but, it has been freaking me out lately. About 6 months ago, I started getting random "contractions" as I would call them (ive never had a baby, but yes I'm comparing the pain to them). I get random PAINFUL cramping that lasts about 10 seconds off and on. Enough to put my on my knees. Not every day, and not when I'm on my period (normal cramping during that time). This pain comes and goes as pleases. I have debated having it removed, but it is my only DEPENDABLE method of birth control that I'm willing to use."