You do not need to have had a child in order to get an IUD. I had one before I got pregnant with my son and I used one after I had him for awhile. The mirena and the implanon are estrogen free methods. The implanon is a matchstick sized implant put under the skin on the inside of your upper arm, it is good for 3 years. The mirena is an IUD good for 5 years, it tends to make periods lighter and be compatible with smokers. It's uncomfortable to have it inserted but taking a few ibuprofen helps and after a day or two things tend to feel fairly normal. So far the moms I've talked to who have had the implanon have liked it and said that getting it put it was relatively painless, numbing shot in arm and some soreness after.