Intrauterine devices (IUDs) are small, flexible “T” shaped devices that can be inserted by a clinician into the uterus. The various IUDs (Kyleena, Liletta, Mirena, ParaGuard and Skyla) work in many ways to prevent pregnancy, not all of them fully understood by research, but it is clear that IUDs do work before conception ever occurs. The way an IUD works is by preventing fertilization of the egg either with hormones or copper ions. The ParaGard copper-style IUD works by releasing small amounts of copper inside the uterus, which works to limit sperm mobility and creates an inhospitable environment for the sperm to live. If you choose an IUD that has hormones such as the Mirena, Skyla or Liletta the small amount of hormones released inside the uterus work by inhibiting ovulation and thickening cervical mucus which also limits sperm mobility, and keeps the lining of the uterus very thin. IUDs last many years depending upon the type you choose. Skyla, Kyleena and Liletta last between 3 and 5 years. Mirena lasts for up to 7 years and ParaGuard lasts 10 to 12 years. Fertility is also immediately returned upon removal of the device.