How Effective is an Intrauterine Device?

By Lillian Downey

  • Overview

    IUDs, or Intrauterine Devices, are long-term internal birth control solutions for women. They are t-shaped devices about the size of a penny that a health care provider inserts into the woman's uterus. There are two kinds of IUDs currently on the market: copper and progesterone. As with all birth control, the IUDs effectiveness is judged by two criteria. Perfect use means that the product is inserted and remains at the exact prescriptive level for its duration of use. And, average use measures how the device works for women who may occasionally use the birth control incorrectly. Both kinds of devices have similar rated of effectiveness, with minute differences.
  • Progesterone IUD

    The most common progesterone IUD on the market is the Mirena. Mirena, once inserted, slowly releases a steady and small stream of levonorgestrel into the uterus. Once inserted, Mirena can be worn for up to 5 years, but can be removed at any time by a health care provider when a woman decides she wants to become pregnant. Progesterone IUDs are very effective. They boast a 99.9% effectiveness rate with both perfect and imperfect use.
  • Copper IUD

    The most widely used copper IUD on the market is called Paraguard. Paraguard is similar to Mirena, in that is a small, plastic t-shaped device that is inserted into the uterus, but unlike Mirena, Paraguard does not contain hormones. Instead Paraguard has a copper coated segment that helps create an environment in the uterus where pregnancy is unlikely to occur. Because it does not contain hormones, Paraguard can be worn for 10 years. Copper IUDs have equally high effectiveness ratings. With perfect use, Copper IUDs are 99.4% effective and with average use, they are 99.2% effective.


  • Maintaining Effectiveness

    Although IUD failure rates are exceptionally low, there are still things women can do to make sure they get the maximum benefit of their devices. First, a woman fitted with an IUD should check her strings on a regular basis to make sure the IUD hasn't slipped, become loose or displaced. This is a rare side effect that can happen after insertion. If she cannot find her strings, or feel her strings have moved, she should consult her healthcare provider immediately and use a back up for of birth control. Secondly, a woman can have her strings checked ad recommended by her health care provider. This can detect a more subtle movement of the IUD that may be hard to detect at home. Once IUDs are inserted, they are relatively maintenance free and can offer a woman years of reliable protection from pregnancy. IUDs do not protect women from contracting sexually transmitted infections.
  • Back up Methods

    Because of IUD,s high rates of effectiveness, it is not necessary to use a back up method of birth control to prevent pregnancy. It is important to note that IUDs cannot protect you from sexually transmitted infections, so many women still opt to use condoms while using and IUD. A health care provider may prescribe birth control pills to persons using an IUD to take for a short time to reduce cramps and bleeding that can be associated with a new IUD. These are not for the purposes of preventing pregnancy.
  • Getting Pregnant in the Future

    IUDs can be removed at any time by a heath care provider. If a woman decides she wants to become pregnant, she can simpy have her IUD removed. Fertility is usually restored in one menstrual cycle or less after removing the IUD. If after the pregnancy, the woman wishes to continue using an IUD as her preferred method of birth control, she can simply have a new one inserted by her doctor. A women should never attempt to remove her own IUD to avoid the risk of puncturing the uterus.
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