The Intrauterine Device (IUD): A Long-acting Reversible Contraception

Revised 2012

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Birth control methods are different in how well they work. Each birth control method has its own risks. There are also risks that happen when the birth control method is not used correctly. Eighty-five out of 100 women who do not use any birth control will get pregnant over one year. Even if birth control is used correctly, some methods will fail. For example, male condoms can fail 1-2 times in 10 uses. Birth control pills fail about 8 to 11 times out of 100 even though most people think the birth control pill keeps a woman from getting pregnant almost all the time. The pill usually fails because it is not used correctly.

IUDs.pngOne group of methods that is becoming more popular for many women is Long-Acting Reversible Contraception (LARC). These methods do not fail as often and fewer women become pregnant because they are always in place and last for a long time. Because of this, the failure rate is less than 1 in 100. LARC methods reduce the number of times women get pregnant when they do not want to, called unintended pregnancy. The number of abortions is also lower when women use LARC. LARC methods include subcutaneous (under the skin) implants, intrauterine devices (IUDs), and injectable methods (a shot). The shot fails at a higher rate than other LARC methods because it does not last as long. LARC methods also help women in other ways and there are very few reasons they cannot be used. This page will tell you more about IUDs.


IUDs are small, bendable implants shaped like a T that are put inside a woman’s uterus (womb). There are two kinds of IUDs in the US: the copper IUD and hormone IUD. The copper IUD is wrapped with coils that put small amounts of copper into the uterus, which harms sperm, and can be left in place for up to 10 years. The hormone IUD has progestin, a man-made hormone that thickens the mucus in mouth of the womb (at the cervix) to keep sperm from going into the uterus. It also changes the inside of the uterus so that menstrual bleeding is lighter. Hormone IUDs can be used for up to 5 years. Most women with a hormone IUD do not bleed as much with their periods and have fewer cramps after the first few months. IUDs must be put in and taken out by a doctor or nurse practitioner. IUDs do not keep you from getting infections that are passed from one person to anther during sex.

IUDs are used by 40 out of 100 women in China and 10 to 30 out of 100 women in Latin America and Europe, but in the US only about 6 out of 100 women use IUDs.

What are some of the concerns about IUDs?

In the past, some women in the US have worried about using IUDs because they thought IUDs might cause an infection in their lower belly (pelvis) or prevent them from being able to have a child. Research studies have shown this is not true. In fact, infection only happens within the 3 weeks after the IUD is put in. The chance of getting a sexually transmitted infection is the same with or without an IUD. Also, the chance of not being able to get pregnant due to scarring of the fallopian tubes is no higher than when an IUD is not used. Studies show that a woman using an IUD has the same chance of having scarred tubes as other women with the same number of sexual partners and infections. This scarring is mainly linked with chlamydia infection (sexually transmitted infection), and not the IUD itself.

Who can use an IUD?

Before 2005, IUDs were used mainly by women who had at least one child, had no history of pelvic infections and who had a sexual relationship with just one partner. In 2005, the US Food and Drug Administration said using the copper IUD was okay for women who had never had a child and who had more than one sexual partner. In 2012, the American Congress of Obstetricians and Gynecologists (ACOG) said that both IUDs could be used by teens, unless the teen had a pelvic infection in the past. This makes IUDs a good form of birth control for many more women.

Are there women who should not use an IUD?

The US Centers for Disease Control has rules for birth control called Medical Eligibility Criteria (CDC MEC). These rules look at different diseases and health conditions and the kinds of birth control that can be used with them. If an IUD can be used by women with a certain disease without problems, then it is a Category 1. For example, obesity (being overweight) is a Category 1 condition, so IUDs can be used by obese women.

A Category 2 condition is when the IUD can be used, but a health care provider should follow the woman more closely. Examples of Category 2 problems are diabetes and emphysema.

Category 3 is a condition where an IUD generally would not be recommended, and a health care provider should carefully consider other options.

Category 4 is a disease or problem that an IUD cannot be used with, such as in women with an active pelvic infection.

Both the copper and hormone IUDs are listed in Category 1 or 2 for most health conditions.


Hormone and copper IUDs are safe, long-acting methods of birth control that work well. They can be used by many different women, even those with health conditions. Past fears and worries about IUDs are mostly not true, as studies have not shown that IUDs cause infections or scarring of the tubes that could keep a woman from being able to get pregnant. Talk with your healthcare provider about whether the IUD is right for you.


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