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These documents are for informational purposes only and are not intended to constitute medical advice, diagnosis, or treatment.
Intrauterine Devices

The Basics

The letters "IUD" stand for "intrauterine device."

IUDs are small, "T-shaped" contraceptive devices made of flexible plastic. IUDs are available by prescription only. A woman and her clinician decide which is the right type for her, and the clinician inserts it in her uterus to prevent pregnancy. Two types are now available in the U.S.:

  • ParaGard (Copper T 380A) — contains copper and can be left in place for 12 years
  • Mirena — continuously releases a small amount of the hormone progestin, and is effective for five years

How IUDs Work

Both kinds of IUDs work by preventing sperm from joining with an egg by affecting the way they move. The hormone in Mirena increases effectiveness. It thickens cervical mucus, which provides a barrier that prevents sperm from entering the uterus. It also prevents some women's ovaries from releasing eggs (ovulation).

IUDs also alter the lining of the uterus. In theory, this may prevent pregnancy by preventing the implantation of a fertilized egg — but this has not been scientifically proven.

IUDs have a string attached that hangs down through the cervix into the vagina. A woman can make sure the IUD is in place by feeling for the string in her vagina. A clinician uses the string to remove the IUD.


The IUD is one of the most effective reversible methods of birth control. Of 100 women who use ParaGard or Mirena, one or fewer will become pregnant during the first year of typical* use. Fewer than one will become pregnant with perfect** use. Fewer pregnancies occur with continued use.

It is very important to remember that the IUD does not protect against sexually transmitted infections. Use a latex or female condom with the IUD to reduce the risk of infection.

*Typical use refers to failure rates for women whose use is not consistent or always correct.
**Perfect use refers to failure rates for those whose use is consistent and always correct.


IUDs are the most popular form of reversible birth control in the world. More than 85 million women use them.

IUDs may improve a woman's sex life. There is nothing to put in place before intercourse to protect against pregnancy. Some women say they feel free to be more spontaneous because they do not have to worry about becoming pregnant.

ParaGard does not change a woman's hormone levels.

Mirena may reduce menstrual cramps and flow. Average flow is reduced by 90 percent. Flow stops altogether for about 20 percent of women within one year. Reduced flow may reduce iron deficiency anemia.

The ability to become pregnant returns quickly when IUD use is stopped.

The IUD is one of the most private methods of birth control.  No one can tell you’re using it. There is no packaging or other evidence of use that might embarrass some users.

The IUD as Emergency Contraception
The ParaGard IUD can reduce the risk of pregnancy by 99.9 percent if inserted within five days after unprotected vaginal intercourse.

Possible Side Effects

Possible side effects that usually clear up after the first several weeks to months include —

  • changes to menstrual flow
    • Spotting between periods is common with IUD use.
    • ParaGard may cause a 50 to 75 percent increase in menstrual flow. In some cases this may lead to anemia.
  • menstrual cramps or backaches

Possible Complications

Serious problems with the IUD are rare. Report problems to your clinician right away to avoid further complications.

Expulsion — Occasionally, the IUD will partially or completely slip out of the uterus. It is more likely among younger women and women who have never had a baby. If it happens, a woman can become pregnant. If partially expelled, the IUD must be removed.

Perforation — Very rarely, the IUD is pushed through the wall of the uterus during insertion. Although it sounds painful, it usually isn't. Perforation is usually discovered and corrected right away. If not, the IUD can move into other parts of the pelvic area, and could damage internal organs. Sometimes surgery is needed to remove the IUD.

Infection — Pelvic infection associated with IUD use is rare. It is caused by bacteria getting into the uterus during insertion. Most infection develops within three weeks of insertion. Infection after three weeks is very rare. It usually happens through exposure to sexually transmitted infections such as chlamydia or gonorrhea. Pelvic infections left untreated can cause sterility.

Tell your clinician immediately if you ...
  • find that the string length has become shorter or longer
  • are not able to feel the string
  • feel the hard plastic bottom of the "T" of the IUD against the cervix
  • think you might be pregnant
  • have periods that are much heavier or last much longer than usual
  • have
    • severe abdominal cramping, pain, or tenderness in the abdomen
    • pain or bleeding during sex
    • unexplained fever and/or chills
    • flu-like symptoms - muscle aches, fatigue
    • unusual vaginal discharge
    • a missed, late, or unusually light period
    • unexplained vaginal bleeding

Pregnancy — Most pregnancies happen to IUD users when their IUDs slip out without their knowing it. The chance that a pregnancy will happen while an IUD is in place is very low. If it does happen, have the IUD removed, if at all possible, as soon as you know you're pregnant. Women who choose to complete a pregnancy with an IUD in place must have close medical supervision throughout their pregnancy.

If you are pregnant with an IUD in place, there is an increased risk of

  • ectopic (not in the uterus) pregnancy
  • dangerous pelvic infection
  • miscarriage
  • early labor and delivery
Ectopic Pregnancy IUD users are less than half as likely to have an ectopic pregnancy as women who use no contraceptive. A pregnancy that happens while using an IUD, however, is more likely to be ectopic than one that happens when not using an IUD. Warning Signs - Get medical care right away if you have
  • irregular vaginal bleeding
  • pain in the abdomen or tip of the shoulder
  • sudden weakness or fainting
Ectopic pregnancies are life threatening and must be removed.

Who Can Use IUDs

Most healthy women can use an IUD, including younger women who have not had children.

An IUD may be right for you if you

  • want a very effective, long-term, reversible method of birth control
  • are breastfeeding
  • cannot use combined hormone methods because you smoke or have certain medical conditions, such as uncontrolled hypertension
  • do not want to use hormone methods

You should not use the IUD if you

  • have had a pelvic infection following either childbirth or an abortion in the past three months
  • have or may have a sexually transmitted infection or other pelvic infection
  • think you might be pregnant
  • have cervical cancer that hasn't been treated
  • have cancer of the uterus
  • have unexplained bleeding in your vagina
  • have pelvic tuberculosis
  • have, or may have, an allergy to copper or have Wilson's Disease (ParaGard only)
  • have severe liver disease (Mirena only)
  • have, or may have, breast cancer (Mirena only)

Conditions of Increased Risk — Certain conditions or risks may increase the possibility of developing serious complications while using the IUD. These include being at risk for sexually transmitted infections at time of insertion or having

  • had PID — pelvic inflammatory disease — in the past 12 months
  • had two or more sexually transmitted infections within the past two years
  • a history of tubal infection - not a risk if you've had a pregnancy in your uterus since the infection
  • a history of impaired fertility and the desire to get pregnant in the future
  • uncontrolled infections of the cervix or vagina, including bacterial vaginosis
  • to take daily medication(s) containing a corticosteroid, such as prednisone
  • diabetes
  • severe anemia
  • a uterus positioned very far forward or backward in the pelvis
  • large fibroid tumors (not cancer) in the uterus
  • been born with severe abnormalities of the uterus
  • HIV or AIDS
  • blood that doesn't clot sufficiently
  • to take a medication to help your blood clot
  • ovarian cancer or current evaluation for ovarian cancer
  • serious blood clots in deep veins or lungs (Mirena only)

Special Cautions for Teens — A teen may not be able to use an IUD if her uterus is too small — a clinician will tell you if an IUD might be right for you.  Some clinicians may not understand that the IUD is safe and effective for young women and may be unwilling to provide it.

Getting an IUD

You must see a clinician to find out if you can use an IUD.

Your Medical History — Your clinician will ask questions about your medical history and lifestyle. It is very important to be open and honest about your sex life because the IUD isn't right for all women. For example, your clinician will want to know what risks you may take for getting sexually transmitted infections because the IUD provides no protection against them.

The Pelvic Exam — Your clinician will check to be sure your cervix, vagina, and internal organs are normal and not infected. You may be tested for sexually transmitted infections, such as gonorrhea or chlamydia, vaginal infections, precancerous cervical cells, or any other condition that needs to be treated.

Scheduling the Insertion — An IUD can be inserted at any time. However, insertion may be more comfortable midcycle, when the cervix is naturally dilated.

Before insertion

  • Be sure to read the package insert that comes with the IUD.
  • Discuss any questions you have with your clinician.
  • Learn how to watch for possible side effects or other problems.

Getting an IUD After Pregnancy

You can have an IUD inserted

  • up to 48 hours after giving birth OR after waiting at least four weeks after giving birth. Women who are breastfeeding should wait four weeks before having Mirena inserted.
  • immediately after a vacuum aspiration abortion
  • after waiting at least four weeks after a D&E abortion
  • once an ultrasound confirms a medication abortion is complete, at least 14 days after taking mifepristone OR after the first menses following medication abortion

IUD Insertion

Some clinicians tell women to take an over-the-counter painkiller an hour before insertion to lessen the cramps that insertion may cause.

To insert the IUD, the clinician holds the vagina open with a speculum. An instrument called a tenaculum is attached to the cervix to steady the uterus. Then another instrument, called a "sound," may be inserted to measure the length of the cervical canal and uterus.

After the sound is withdrawn, a tube containing the IUD is inserted. The "arms" (T bars) of the IUD are bent back when they enter the uterus through the cervix. The IUD is pushed into place by a plunger in the tube. The arms open into the T shape when the IUD is in the uterus.

The tube, plunger, tenaculum, and speculum are withdrawn. The IUD is left in place with the string hanging down through the cervix into the vagina. The clinician snips the string ends, leaving about one to two inches to hang out of the cervix.

The string can't be seen outside the vagina but is long enough to be felt by a finger inserted in the vagina.

Uterine cramps may be uncomfortable during insertion. Some women feel a bit dizzy, and rarely a woman may faint. Deep, relaxed breathing may help. The cramping eases with a little rest or pain medication. Many women only feel mild discomfort. Women with sensitive cervical tissue may need to have a local anesthetic injected around the cervix to reduce or prevent the pain.

If you have an IUD inserted, you may want to have someone with you to escort or drive you home. You should plan to rest at home until you are comfortable.

After IUD Insertion

Many women adjust to their IUDs very quickly. It may take several weeks or months for others. Heavy bleeding and cramping in the first few months may lead some women to change their minds and ask to have the IUD removed. Many clinicians prescribe medication during the first few months to lessen bleeding and cramps during menstruation. Overall, women's level of satisfaction with the IUD is quite strong — 99 percent of IUD users are pleased with them.

There may be some spotting between periods during the first few months, and the first few periods may last longer, and the flow may be heavier. It is not unusual for a woman to have heavier and longer periods while using an IUD.

Cramping or backache may occur for several days or weeks after insertion. Simple pain medication usually clears up cramping and discomfort. If bleeding or pain is severe and does not seem to lessen, tell your clinician.

You should have a checkup after your first period. Don't wait longer than three months after insertion to make sure your IUD is still in place. Women using an IUD should have regular checkups to make sure everything is all right. This can be done at the time as your periodic gyn exam.

Your clinician will tell you the type of IUD that was inserted and when it should be replaced. Write this information down and keep it in a safe place. Otherwise, clinicians you see in the future will not be able to tell which IUD you have or when it needs to be replaced.

You can resume sexual activity as soon as you like after insertion.

  • ParaGard is effective immediately after insertion.
  • Mirena is effective immediately if inserted within seven days after the start of your period. If you have Mirena inserted at any other time during your menstrual cycle, use another method of birth control if you have vaginal intercourse during the first week after insertion. Protection will begin after seven days.

Checking Your IUD

An IUD is most likely to be expelled during the first few months of use, but this may occur later. Expulsion is most likely to happen during your period. Check your pads, tampons, or cups to see if the IUD has fallen out. If it has, you must check with your clinician. Until then, use another form of birth control such as latex or female condoms.

Feel for the string ends between periods. It is especially important to check every few days for the first few months.

To feel for the string ends ...
  • Wash your hands. Then either sit or squat down.
  • Put your index or middle finger up into your vagina until you touch the cervix. The cervix will feel firm and somewhat rubbery, much like the tip of your nose.
  • Feel for the string ends that should be coming through. If you find them, it means that the IUD is in place and working. However, if the string ends feel longer or shorter than before, it may be that the IUD has moved and needs to be repositioned by a clinician. Be sure to use another form of birth control until it is repositioned.
  • Do not pull on the string ends. Pulling might make the IUD move out of place or even come out.


Having an IUD removed or replaced is usually simple. The clinician carefully tugs on the string at a certain angle, the IUD "arms" fold up, and the IUD slides through the opening of the cervix. Replacing the IUD with a new one can usually be done right after removal. Women should never try to remove IUDs themselves or ask nonprofessionals to do it for them. Serious damage could result.

In rare cases, IUDs become embedded in the uterus and cannot be easily pulled free. In these cases, the cervix may have to be dilated and a surgical tool forceps may be used to free the IUD. A local anesthetic is used for such removals. In very rare cases, surgery becomes necessary. Women may have to be hospitalized for removals that require incision.

The Cost

The IUD is the most inexpensive long-term reversible method of contraception available in the world.

Nationwide, the cost of the exam, insertion, and follow up visit ranges from $175-$500. Costs vary from community to community, based on regional and local expenses. IUD services are priced according to income at some family planning clinics and are covered by Medicaid.

Visit Planned Parenthood®, another family planning clinic, your HMO, or a private health care provider for more information.

Update — Jennifer Johnsen, MPH, July 2005
Original version — 1965

© 2005 Planned Parenthood Federation of America, Inc. All rights reserved.