Intrauterine Devices (IUDs)

The intrauterine device (IUD) is a small plastic T-shaped device that is inserted into the uterus. An IUD's contraceptive action begins as soon as the device is placed in the uterus and stops as soon as it is removed. Precisely how the IUD prevents pregnancy is a mystery. They may kill sperm or preven them from moving, which prevents fertilization from occurring. They may also stop a fertilized egg from implanting in the uterus. IUDs have an effectiveness rate of close to 100%. They are also a reversible form of contraception. Once the device is removed, a woman regains her fertility.

The intrauterine device shown uses copper as the active contraceptive, others use progesterone in a plastic device. IUDs are very effective at preventing pregnancy (less than 2% chance per year for the progesterone IUD, less than 1% chance per year for the copper IUD). IUDs come with increased risk of ectopic pregnancy and perforation of the uterus and do not protect against sexually transmitted disease. IUDs are prescribed and placed by health care providers.
IUD Forms
Two types of IUDs are available in the United States:

Copper-Releasing (ParaGard) can remain in the uterus for up to 10 years.
Progestin-Releasing (Mirena) can remain in the uterus for up to 5 years. Mirena is also known as a levonorgestrel-releasing intrauterine system, or LNG-IUS. The LNG-IUS is long-acting, safe, very effective in preventing heavy bleeding, and helps reduce cramps. In fact, some experts describe it as a nearly ideal contraceptive. It is also proving beneficial for women with menstrual disorders, (particularly heavy bleeding).

Inserting the IUD
With some exceptions, an IUD can be inserted at any time, except during pregnancy. It is typically inserted in the following manner by a trained health professional:

A plastic tube containing the IUD (the inserter) is slid through the cervical canal into the uterus.

A plunger in the tube pushes the IUD into the uterus.
Attached to the base of the IUD are two thin but strong plastic strings. After the instruments are removed, the health care provider cuts the strings so that about an inch of each dangles outside the cervix within the vagina.
The strings have two purposes:

They enable the user or health care provider to check that the IUD is properly positioned. (Because the IUD has a higher rate of expulsion during menstruation, the woman should also check for the strings after each period, especially if she has heavy cramps.)

They are used for pulling the IUD out of the uterus when removal is warranted.
Candidacy for the IUD

The IUD is often an excellent choice for women who do not anticipate future pregnancies, but who do not wish to be sterilized. Women who are unable to use hormonal contraceptives (for example, those with heart disease, epilepsy, migraines, hypertension, or liver disease) may be good candidates for the copper IUD.

Women with risk factors that preclude hormonal contraceptives should probably avoid progestin-releasing IUDs, although the progestin doses are much lower with LNG-IUS and probably do not pose the same risks. Other women who may be poor candidates for the IUD are those with the following history or conditions:

Current or recent history of pelvic infection
Risk factors for sexually transmitted diseases (such as having multiple sexual partners)

History of menstrual disorders. (Progestin-releasing IUDs may be an option for women with heavy or painful bleeding. They should avoid the copper-releasing IUDs, however.)
Current pregnancy
Abnormal Pap tests
Cervical or uterine cancer
A very large or very small uterus
Advantages of the Intrauterine Device

The IUD is one of the safest, least expensive, and most effective contraceptive devices available. In spite of its clear advantages and current safety record, only 1% of American women currently use the IUD. (Over 10% of European women have chosen the IUD.) This low use in America is mainly due to persisting and now unwarranted fears of serious infection. [See Infection below. ]

IUDs have the following advantages:

The IUD is more effective than OCs at preventing pregnancy and it is reversible. Once it is removed, fertility returns. (In spite of outdated concerns, studies have found no adverse effects on fertility with the current IUDs.)
Unlike the pill, there is no daily routine to follow.

Unlike the barrier methods (spermicides, diaphragm, cervical cap, and the male or female condom), there is no insertion procedure to cope with before or during sex.
Intercourse can resume at any time, and as long as the IUD is properly positioned, neither the user nor her partner typically feels the IUD or its strings during sexual activity.

It is the least expensive form of contraception over the long term.
There are also additional advantages, depending on the specific IUD:

The progestin-releasing LNG-IUS (Mirena) is now considered to be one of the best options for treating menorrhagia (heavy menstrual bleeding). (However, irregular breakthrough bleeding can occur during the first 6 months.) Some studies suggest it might help avoid hysterectomy in 80% of cases. It may even be appropriate and protective for women with uterine fibroids.

The copper-releasing IUDs do not have hormonal side effects and may help protect against endometrial (uterine) cancer.

Disadvantages and Complications of Specific Intrauterine Devices
The insertion procedure can be painful and sometimes causes cramps, but for many women it is painless or only slightly uncomfortable. Patients are often advised to take an over-the-counter painkiller ahead of time. They can also ask for a local anesthetic to be applied to the cervix if they are sensitive to pain in that area. Occasionally a woman will feel dizzy or light-headed during insertion. Some women may have cramps and backaches for 1 - 2 days after insertion, and others may suffer cramps and backaches for weeks or months. Over-the-counter painkillers can usually moderate this discomfort.

Menstrual Bleeding. Both IUD forms have effects on menstruation, although they differ significantly by type:

Copper releasing IUDs can cause cramps, longer and heavier menstrual periods, and spotting between periods. Prescription medications are available to control the bleeding and pain, which, in any event, usually subside after a few months.
Progestin-releasing IUDs produce irregular bleeding and spotting during the first few months. Bleeding may disappear altogether. (This characteristic is a major advantage for women who suffer from heavy menstrual bleeding but may be perceived as a problem for others.)

Menstrual difficulties can be so troublesome with either IUD that, according to one study, they were responsible for a removal rate of 5 - 15% within a year of insertion.

Infection. The current versions of IUD pose a slightly higher risk for pelvic inflammatory disease in the first month following insertion. The risk of PID in women without any symptoms of sexually transmitted infections, however, is the same in both IUD users and nonusers. An early IUD, the Dalkon Shield, which had a braided tail, was banned after reports of several deaths and a very high rate of infection. The newer types of IUDs are much safer and do not pose as high risk for infection. Still, some doctors may prescribe antibiotics as a precaution before insertion.

Ovarian Cysts. The LNG-IUS may increase the risk for ovarian cysts, but such cysts usually do not cause symptoms and resolve on their own.

Expulsion. An estimated 2 - 8% of IUDs are expelled from the uterus within the first year. Expulsion is most likely to occur during the first 3 months after insertion. Expulsion rates may be higher than average if the IUD is inserted immediately after delivery of a child. In 1 in 5 cases, the woman fails to notice that the device is gone, and thus faces the risk of unintended pregnancy. The risk for expulsion is highest during menstruation, so women should be sure to check the strings to make sure the IUD is in place.

Effects on Pregnancy. None of the current IUDs increase the risk for infertility. In the very unlikely event that a woman conceives with an IUD in place, however, there is a higher risk of an ectopic pregnancy or miscarriage.


If the IUD is removed right after conception, the risk for miscarriage is close to average (about 20%). There is no evidence that the IUD in a pregnant woman increases the risk for birth defects in the infant.

Perforation. A potentially serious complication of the IUD is the accidental perforation of the uterus during insertion or later perforation if the IUD shifts position. Such an occurrence is very rare, and the risk is higher or lower depending on the skill of the doctor.