Etonogestrel
"I got the Nexplanon in September of 2013. I have had no period til recently (July 2015). It will I for two weeks then stop for about 4 days then start up again.  I have also gained an extreme amount of weight, 65 lbs, and I can't get it off of me to save my life.  I'm going back to the Gyno next week but this is the most dreadful experience ever right now and I'm not scheduled to get it out til next September.  (2016)"