Mirena

Mirena is a form of birth control that releases daily amounts of the hormone levonorgestrel (a type of progestin) into the uterus. Once the T-shaped plastic intrauterine device (IUD) has been inserted by a health care professional, patients must check its threads once a month to ensure it is still properly in place.
Although there is no single explanation for how Mirena works, it can prevent pregnancy by thickening cervical mucus, preventing sperm from reaching the egg by generating a toxic environment, thinning the uterine lining, and, in some cases, stopping the release of eggs from the ovary. Mirena is 99 percent effective at preventing pregnancy, and works up to five years.
Who Might Use Mirena
Mirena is intended for women seeking effective, easy-to-use and reversible forms of birth control. Ideally, women will have had at least one baby before using Mirena, since the product can lead to infertility.
Benefits
According to its manufacturer, Bayer Pharmaceuticals, Mirena offers more flexible family planning options since in most cases patients can conceive immediately after the device is removed (80 percent within 12 months of removal). The system also releases fewer hormones and keeps levels steadier than birth control pills.
Dangers
Mirena does not protect against sexually transmitted diseases (STDs). The FDA warns that Mirena has been associated with sepsis, pelvic inflammatory disease, embedded IUDs, perforation of the uterine wall or cervix, expulsion, ovarian cysts and breast cancer tumors. If pregnancy occurs, Mirena must be removed.
Precautions
Mirena should not be used if patients have a suspected pregnancy, anomalies of the uterus, pelvic inflammatory disease, endometriosis, abnormal pap smears, suspicious genital bleeding, cervicitis or vaginitis, liver disease or tumors, breast carcinomas, other IUDs still in place or sensitivities to materials used to make the product.
History
Mirena was introduced to the market in Finland in 1990 and has since been approved for use in more than 100 other countries. The FDA approved Mirena for the American market in 2000.