Intrauterine device (IUD) for birth control
An IUD is a small, T-shaped plastic device that is wrapped in copper or contains hormones. The IUD is inserted into your uterus by your doctor. A plastic string tied to the end of the IUD hangs down through the cervix into the vagina. You can check that the IUD is in place by feeling for this string. The string is also used by your doctor to remove the IUD.
Types of IUDs
- Levonorgestrel (LNg) IUD. The levonorgestrel (LNg) IUD, also known as Mirena, releases levonorgestrel, which is a form of progestin. The LNg IUD appears to be slightly more effective at preventing pregnancy than the copper IUD. Also, unlike other IUDs, it may reduce the risk of pelvic inflammatory disease (PID). The LNg IUD is effective for at least 5 years.
- Copper IUD. The most commonly used IUD is the copper IUD (such as Paragard). Copper wire is wound around the stem of the T-shaped IUD. The copper IUD can stay in place for at least 10 years and is a highly effective form of contraception.
How it works
Both types of IUD prevent fertilization of the egg by damaging or killing sperm. The IUD also affects the uterine lining (where a fertilized egg would implant and grow).
- LNg IUD. This IUD prevents fertilization by damaging or killing sperm and making the mucus in the cervix thick and sticky, so sperm can't get through to the uterus. It also keeps the lining of the uterus (endometrium) from growing very thick.1 This makes the lining a poor place for a fertilized egg to implant and grow. The hormones in the LNg IUD also reduce menstrual bleeding and cramping.
- Copper IUD. Copper is toxic to sperm. It makes the uterus and fallopian tubes produce fluid that kills sperm. This fluid contains white blood cells, copper ions, enzymes, and prostaglandins.1
You can have an IUD inserted at any time, as long as you are not pregnant. An IUD is inserted into your uterus by your doctor. The insertion procedure takes only a few minutes and can be done in a doctor's office. Sometimes a local anesthetic is injected into the area around the cervix, but this is not always needed.
IUD insertion is easiest in women who have had a vaginal childbirth in the past.
Your doctor may have you feel for the IUD string right after insertion, to be sure you know what it feels like. You may be given antibiotics to prevent infection.
What To Expect After Treatment
You may want to have someone drive you home after the insertion procedure. You may experience some mild cramping and light bleeding (spotting) for 1 or 2 days.
Your doctor may want to see you 4 to 6 weeks after the IUD insertion, to make sure it is in place.
Be sure to check the string of your IUD after every period. To do this, insert a finger into your vagina and feel for the cervix, which is at the top of the vagina and feels harder than the rest of your vagina (some women say it feels like the tip of your nose). You should be able to feel the thin, plastic string coming out of the opening of your cervix. It may coil around the cervix, which can make it difficult to find. Call your doctor if you cannot feel the string or the rigid end of the IUD.
If you cannot feel the string, it doesn't necessarily mean that the IUD has been expelled. Sometimes the string is just difficult to feel or has been pulled up into the cervical canal (which will not harm you). An exam and sometimes an ultrasound will show whether the IUD is still in place. Use another form of birth control until your doctor makes sure that the IUD is still in place.
If you have no problems, check the string after each period and return to your doctor once a year for a checkup.
- The copper IUD is approved for use for up to 10 years.
- The LNg IUD is approved for use for up to 5 years.
Why It Is Done
You may be a good candidate for an IUD if you:
- Do not have a pelvic infection at the time of IUD insertion.
- Have only one sex partner who does not have other sex partners and who is infection-free. This means you are not at high risk for sexually transmitted diseases (STDs) or pelvic inflammatory disease (PID), or you and your partner are willing to also use condoms.
- Want an effective, long-acting method of birth control that requires little effort and is easily reversible.
- Cannot or do not want to use birth control pills or other hormonal birth control methods.
- Are breast-feeding.
The copper IUD is recommended for emergency contraception if you have had unprotected sex in the past few days and need to avoid pregnancy and you plan to continue using the IUD for birth control. As a short-term type of emergency contraception, the copper IUD is more expensive than emergency contraception with hormone pills.
How Well It Works
The IUD is a highly effective method of birth control.1
- When using the LNg IUD, about 1 out of 1,000 women becomes pregnant in the first year. Over 5 years of use, only about 7 women out of 1,000 become pregnant.2
- When using the copper IUD, about 6 per 1,000 women become pregnant in the first year. Over 10 years of use, about 20 to 30 women out of 1,000 become pregnant.2
- Most pregnancies that occur with IUD use happen because the IUD is pushed out of (expelled from) the uterus unnoticed. IUDs are most likely to come out in the first few months of IUD use, after being inserted just after childbirth, or in women who have not had a baby.
Additional advantages of the LNg IUD
In addition, the LNg IUD:
- Reduces heavy menstrual bleeding by an average of 90% after the first few months of use.3
- Improves irregular (spotting and prolonged) menstrual bleeding after 3 to 4 months.3
- Reduces menstrual bleeding and cramps and, in many women, eventually causes menstrual periods to stop altogether. In this case, not menstruating is not harmful.
- May prevent endometrial hyperplasia or endometrial cancer.
- May decrease the risk of pelvic inflammatory disease (PID).
- May effectively relieve endometriosis and is less likely to cause side effects than high-dose progestin.4
- Reduces the risk of ectopic pregnancy.
- Does not cause weight gain.
Risks of using an intrauterine device (IUD) include:
- Menstrual problems. About 12% of women have the copper IUD removed because of increased menstrual bleeding or cramping.2 Women may also experience spotting between periods. But after about 3 months of increased bleeding or spotting, the LNg IUD reduces menstrual cramps and bleeding by an average of 90%.2
- Perforation. In 1 out of 1,000 women, the IUD will get stuck in or puncture (perforate) the uterus.1 Although perforation is rare, it almost always occurs during insertion. The IUD should be removed if the uterus has been perforated.
- Expulsion. About 2% to 10% of IUDs are pushed out (expelled) from the uterus into the vagina during the first year. This usually happens in the first few months of use. Expulsion is more likely when the IUD is inserted right after childbirth or in a woman who has not carried a pregnancy.1 When an IUD has been expelled, you are no longer protected against pregnancy.
Disadvantages of IUDs include the high cost of insertion, no protection against STDs, and the need to be removed by a doctor.
Disadvantages of the LNg IUD
The LNg IUD may cause noncancerous (benign) growths called ovarian cysts, which usually go away on their own.
The LNg IUD can cause hormonal side effects similar to those caused by oral contraceptives, such as breast tenderness, mood swings, headaches, and acne. This is rare. When side effects do happen, they usually go away after the first few months.
Pregnancy with an IUD
If you become pregnant with an IUD in place, your doctor will recommend that the IUD be removed. This is because the IUD can cause miscarriage or preterm birth (the IUD will not cause birth defects). Taking out an IUD early in a pregnancy lowers risks of miscarriage or preterm birth. But IUD removal can also cause a miscarriage. As a pregnancy progresses, miscarriage risk is lower if an IUD is removed than if it is left in place.1
When to call your doctor
When using an IUD, be aware of warning signs of a more serious problem related to the IUD.
Call your doctor immediately if you have any of the following symptoms. Remember the word "PAINS." Each letter stands for a word associated with a problem:
- Period is late with a copper IUD, or you have abnormal spotting or severe bleeding
- Abdominal pain, severe cramping, or abdominal pain with sexual intercourse
- Infection with or exposure to a sexually transmitted disease (STD) or symptoms of a vaginal infection, such as abnormal vaginal discharge
- Not feeling well or having a fever of 100.4°F (38°C) or higher
- Strings from IUD are missing or are longer or shorter than normal
Call your doctor to schedule an appointment if you:
- Cannot feel the strings of your IUD. (Use condoms as backup birth control until your doctor has checked your IUD.)
- Have severe or prolonged vaginal bleeding.
- Miss a menstrual period, unless you have the LNg IUD. It is normal to miss a period or stop menstruating while you are using the LNg IUD, and this is not a cause for concern. If you have an LNg IUD and miss your period and wonder if you are pregnant, talk with your doctor. IUDs are highly effective, but if you are concerned, you may want to have a pregnancy test to find out for sure.
What To Think About
The IUD is most likely to work well for women who have been pregnant before. Women who have never been pregnant are more likely to expel the IUD or have more pain and cramping after insertion. But they can still use the IUD.1
Pelvic inflammatory disease (PID) concerns have been linked to the IUD for years. But it is now known that the IUD itself does not cause PID. Instead, if you have a genital infection when an IUD is inserted, the infection can be carried into your uterus and fallopian tubes. If you are at risk for a sexually transmitted disease (STD), your doctor will test you and treat you if necessary, before you get an IUD.
Intrauterine devices reduce the risk of all pregnancies, including ectopic (tubal) pregnancy. But if a pregnancy does occur while an IUD is in place, it is a little more likely that the pregnancy will be ectopic. Ectopic pregnancies require medicine or surgery to remove the pregnancy. Sometimes the fallopian tube on that side must be removed as well.
IUD use and medical conditions
An IUD can be a safe birth control choice for women who:5
- Have a history of ectopic pregnancy. Both the copper IUD and LNg IUD are appropriate.
- Have a history of irregular menstrual bleeding and pain. The LNg IUD may be appropriate for these women and for women who have a bleeding disorder or those who take blood thinners (anticoagulants).
- Have a risk for bacterial endocarditis. Antibiotics would be used at the time of insertion and removal to prevent infection.
- Have diabetes.
- Are breast-feeding.
- Have a history of endometriosis. The LNg IUD is a good choice for women who have endometriosis.
IUDs may not be a good choice if you:
- Have never been pregnant (you are more likely to have pain with an IUD and are more likely to have the IUD come out after it is inserted).
- Have a sexually transmitted disease (STD) currently or had one within the past 3 months.
- Are not willing to use condoms to protect yourself from sexually transmitted diseases.
- Have an active infection of your vagina or cervix.
- Have pelvic inflammatory disease (PID) or have a recent history of PID.
- Have a bleeding disorder or take blood-thinners (anticoagulants). Although you cannot use the copper IUD, you can use the LNg IUD.
- Have a history of problems with IUDs.
- Have abnormalities of your uterus.
- Have a uterine infection after childbirth or a septic abortion.
- Have uterine bleeding of unknown origin.
- Have an allergy to copper, so the copper IUD would not be an option.
If you have one of the older, all-plastic IUDs, such as the Lippes Loop, ask your doctor at your next checkup about replacing this IUD with a more effective copper or hormonal one.
- Grimes DA (2004). Intrauterine devices (IUDs). In RA Hatcher et al., eds., Contraceptive Technology, 18th ed., pp. 495–530. New York: Ardent Media.
- Zieman M, et al. (2007). Managing Contraception for Your Pocket. Tiger, GA: Bridging the Gap Foundation.
- Hatcher RA, et al. (2005). Pocket Guide to Managing Contraception 2005–2007. Tiger, GA: Bridging the Gap Foundation.
- Speroff L, Fritz MA (2005). Endometriosis. In Clinical Gynecologic Endocrinology and Infertility, 7th ed., pp. 1103–1133. Philadelphia: Lippincott Williams and Wilkins.
- Speroff L, Darney PD (2005). Intrauterine contraception. In Clinical Guide for Contraception, pp. 221–257. Philadelphia: Lippincott Williams and Wilkins.
Last Updated: May 22, 2008