What Is It?

The intrauterine device (IUD) is a T-shaped piece of plastic about the size of a quarter that is placed inside the uterus to prevent pregnancy. Two types of IUDs are available — one is covered with copper, the other releases the hormone progesterone.

How Does It Work?

The copper-coated IUD primarily prevents pregnancy by not allowing the sperm to fertilize the egg. It may also make it harder for a fertilized egg to implant in the uterus. When an IUD is coated with progesterone, it works in a similar way, but may also thicken the cervical mucus, which prevents sperm from entering the uterus and possibly prevent ovulation (the release of an egg during the monthly cycle).

How Well Does It Work?

Over the course of 1 year, fewer than 1 out of 100 typical couples using an IUD will have an accidental pregnancy. In fact, studies indicate that the IUD is one of the most effective and safest methods of birth control. Although the IUD is an effective method of birth control, it can come out of place and therefore should be checked regularly to be sure it is in place.

In general, how well each type of birth control method works depends on a lot of things. These include whether a person has any health conditions or is taking any medications or herbal supplements that might interfere with its use. The copper IUD allows some flexibility for girls who cannot use a hormonal method of birth control (such as the Pill, ring, or patch). The IUD can also provide a long-term form of birth control.

Protection Against STDs

The IUD does not protect against sexually transmitted diseases (STDs). For those having sex, condoms must always be used along with the IUD to protect against STDs. One of the concerns with the IUD is that girls who have multiple partners and do not use condoms can be at greater risk for STDs, and there's the possibility that these diseases could develop into a pelvic infection. This is true, though, for all methods of birth control.

Abstinence (not having sex) is the only method that always prevents pregnancy and STDs.

Possible Side Effects

The most common side effects of the IUD include:

  • spotting in between periods
  • heavier periods with more cramps with the copper IUD
  • irregular or loss of periods with use of the hormonal IUD
  • expulsion, or loss of the IUD. For some IUD users — particularly teens — the IUD can fall out or become displaced and not work properly.
  • acne, breast tenderness, headaches, and nausea with the hormonal IUD

Rare problems include:

  • perforation of the uterus — there's a very minimal risk of the device perforating the wall during its insertion
  • an infection from bacteria getting into the uterus during insertion

In the past, one type of IUD increased a woman's risk of pelvic inflammatory disease (an infection in the upper part of a woman's reproductive system). That early type of IUD has been taken off the market and testing of the current IUDs indicate that the risk of infection is very small. Some doctors recommend testing for STDs before having an IUD inserted in order to help avoid a pelvic infection. And in order to help prevent future infections, condoms should always be used with IUDs.

The other concern that women have with IUDs is the possibility of ectopic pregnancies, which is when a fertilized egg implants somewhere other than in the uterus. However, doctors have found that girls with an IUD have a lower risk of having an ectopic pregnancy than girls who do not use any birth control.

Who Uses It?

IUDs are safe and effective for many teens. However, it is more common for IUDs to come out by mistake in women who haven't had a baby, as well as in teen girls. When an IUD comes out, a girl may not even know it, leaving her unprotected. So women with IUDs, especially teens, need to check them regularly.

IUDs sometimes need to be removed if a woman gets an STD. Having multiple sex partners can increase the risk of getting an STD. So, IUDs may not be right for girls who have multiple sex partners or who have sex with someone who has multiple partners.

If you're interested in using an IUD, talk to your doctor to see if it's a good birth control option for you.

How Do You Get It?

An IUD must be inserted into the uterus by a doctor. It is often easiest to insert during a girl's period. Copper IUDs need to be replaced by a doctor about every 10 years. IUDs with hormones must be replaced more frequently — up to every 5 years.

How Much Does It Cost?

An IUD costs about $200 to $400 plus the cost of having a doctor insert and remove it, as well as follow-up visits. Many health insurance plans cover these costs, and family planning clinics (such as Planned Parenthood) may charge much less, and the IUD is effective for several years.

Reviewed by: Larissa Hirsch, MD
Date reviewed: November 2009

Related Sites

National Campaign to Prevent Teen and Unplanned Pregnancy
Planned Parenthood Federation of America
American College of Obstetricians and Gynecologists (ACOG)

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