Levonorgestrel
"So, I was really excited about getting birth control because I wanted to wait until my next pregnancy.  I got Skyla in June 2015. The insertion wasn't bad, but the side effects were. First, I got a really bad pelvic infection caused by Skyla. I was bleeding for a month straight with harsh cramps. Sex has been very uncomfortable, and also decreased my sex drive. I get horrible cramps even if I'm not on my Period, the pain makes me really nauseas. I also experienced weight gain. I get a normal 3-4 day period still. It's been a year and a half and I'm tired of this birth control. The only good thing is that I haven't gotten pregnant for these past 2 years."