Two types of intrauterine devices IUDs are used today: one impregnated with levonorgestrel, which is released little by little, and an IUD with copper only.The Pearl index (which reports the effectiveness of a birth control method) was 0.06 for the IUD impregnated with levonorgestrel, and 0.52 for the copper IUD (FertilSterility 102; e12, 2014).