IUD (Intrauterine Device for Birth Control)

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IUD (intrauterine device) facts

  • Intrauterine devices (IUDs) are a form of birth control that prevents implantation of a fertilized egg in the uterus.
  • IUDs can contain hormones that help prevent the implantation process.
  • Other types of IUDs are copper-containing IUDs.
  • IUDs must be inserted by a health-care professional in the office.
  • Side effects of IUDs can include
    • heavy menstrual flow,
    • bleeding,
    • cramping, and
    • uterine infection.
  • Some IUDs can be left in place for up to 10 years.
  • IUDs can be removed at any time by a health-care professional.
  • IUDs do not provide protection against sexually-transmitted diseases (STDs).

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What are IUDs (intrauterine devices)?

The intrauterine device (IUD) is a method of birth control designed for insertion into a woman's uterus so that changes occur in the uterus that make it difficult for fertilization of an egg and implantation of a pregnancy. IUDs also have been referred to as "intrauterine contraception (IUC). IUDs approved for use in the U.S. contain medications that are released over time to facilitate the contraceptive effect.

The IUD is a small "T"-shaped device with a monofilament tail that is inserted into the uterus by a health care practitioner in the office setting. When inserted into the uterus, the arms of the "T" are folded down, but they then open out to form the top of the "T". The device rests inside the uterus with the base of the T just above the cervix and the arms of the T extending horizontally across the uterus. A short piece of monofilament string attached to the IUD extends through the cervix into the vagina. This string makes it possible to be sure that the IUD is still in the uterus.

Although IUDs are highly effective, no birth control method, except abstinence, is considered to be 100% effective.

How does an IUD work?

It is not fully understood how IUDs work. They are thought to prevent conception by causing a brief localized inflammation that begins about 24 hours after insertion. This causes an inflammatory reaction inside the uterus that attracts white blood cells. The white blood cells produce substances that are toxic or poisonous to sperm. The progesterone-releasing IUDs also cause a subtle change in the endometrial environment that impairs the implantation of the egg in the uterine wall. This type of IUD also alters the cervical mucus, which, in turn, inhibits sperm from passing through the cervix.

IUDs are only available by prescription and must be properly inserted by a health care professional. A pelvic exam is required to insert an IUD. The IUD is inserted into the uterus long as she is not pregnant.

The woman must check her IUD every month to be sure that it is still in place. The woman with an IUD in place will still have normal menstrual periods, although some women notice that flow is heavier. Other women, especially those with a hormone-releasing IUD, may have lighter flow. Sometimes, the uterus expels (pushes out) the IUD. Expulsions may not cause any specific symptoms and can be overlooked. In addition to the woman checking the IUD, the device must also be checked periodically by a health-care professional.

Medically Reviewed by a Doctor on 6/26/2015

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