(levonorgestrel-releasing intrauterine system) Mirena is an intrauterine contraceptive device. It is a small, T-shaped plastic device that is inserted into the uterus by a health care provider and works as a contraceptive by releasing a low dose of levonorgestrel (a synthetic progestin hormone) directly into the uterus. The Food and Drug Administration approved Mirena in 2000. It was also FDA-approved in 2009 to treat heavy menstrual bleeding in women who prefer intrauterine contraception as their method of birth control, the first time that the FDA has approved an intrauterine device for this purpose. On Jan. 14, 2010, the FDA sent a warning letter to Bayer because it “overstates the efficacy of Mirena, presents unsubstantiated claims, minimizes the risks of using Mirena, and includes false or misleading presentations regarding Mirena.” However, this is not a “true” recall date for discovery purposes. Some women who have had Mirena implanted experienced serious and even debilitating or life-threatening side effects. The device may migrate from its original position after being inserted, perforating the uterus or embedding itself in the uterus. In both instances, a doctor must locate and surgically remove the device. Mirena may also migrate outside the uterine cavity and cause adhesions or scarring that can lead to infertility. Depending on the damage caused, affected women may require a complete hysterectomy, and more serious complications could result in death.