Contraceptive coil. Doctor holding a copper intrauterine device (IUD, coil) inside the device used to insert it. An IUD is a small contraceptive device that is inserted into the uterus in order to prevent fertilisation. It can contain either copper or levonorgestrel (synthetic progestogen hormone). Copper acts as a spermicide and copper IUDs primarily work by disrupting sperm mobility and damaging sperm so that they are prevented from joining with an egg. IUDs typically have a life on 5 years, after which they should be removed.