What Is It?
The intrauterine device (IUD) is a piece of plastic that is placed inside the uterus to prevent pregnancy. The most common type of IUD is T-shaped and covered with copper wire. Some IUDs are coated with the hormone progesterone.

How Does It Work?
The copper-coated IUD primarily prevents pregnancy by not allowing the sperm to fertilize the egg. When an IUD is coated with progesterone, the hormone works to prevent ovulation (the release of an egg during the monthly cycle) and thicken the cervical mucus, which prevents sperm from entering the uterus. If an egg is fertilized, the IUD will prevent attachment to the wall of the uterus.

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. Although the IUD is an effective method of birth control, it can come out of place and 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 that might interfere with its use. It also depends on whether the method chosen is convenient - and whether the person remembers to use it correctly all the time.

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.

Possible Side Effects
The most common side effects of the IUD include:

• heavier periods with more cramps
• increased chance of developing pelvic inflammatory disease (PID), which can lead to infertility. PID occurs when a sexually transmitted disease such as gonorrhea or chlamydia spreads past the cervix to infect the reproductive organs.

Who Uses It?
The IUD is not recommended for teens and women who have not had a baby. Up to 10 out of 100 IUDs will come out in the first year after they are put in. This is more common in women who haven't had a baby, which includes many teen girls. When an IUD comes out, a girl may not even know it, leaving her unprotected. Also, many teens who have sex are at risk for getting STDs because they don't protect themselves with condoms. Most doctors won't insert an IUD in a teen because if she gets PID she may never be able to have a baby.

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. Plastic and copper IUDs need to be replaced by a doctor about every 10 years. IUDs with hormones must be replaced more frequently.

How Much Does It Cost?
An IUD costs about $250 plus the cost of having a doctor insert and remove it. Many health insurance plans cover these costs and family planning clinics (such as Planned Parenthood) charge much less.

Remember, abstinence (the decision to not have sex) is the only method that always prevents pregnancy and sexually transmitted diseases (STDs).

Updated and reviewed by: George A. Macones, MD
Date reviewed: April 2003 
Reviewed by: Neil Izenberg, MD

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