IUD (Intrauterine Device)

What Is an IUD?

An IUD, or intrauterine device, is a small, plastic, flexible, T-shaped device that is placed into the uterus (womb) and prevents pregnancy. There are two types of IUDs available in the United States. One type, ParaGard T380A, can be kept in place for up to 10 years. The other type is Mirena which can be kept in place for up to 5 years.

How Do IUDs Work?

Some IUDs contain copper, which is slowly released into the uterine cavity. The copper stops the sperm from making it through the vagina and uterus to reach the egg, thus preventing fertilization.

Some IUDs, such as Mirena, release the hormone progestin, which causes the cervical mucus to become thicker so the sperm cannot reach the egg. The hormone also changes the lining of the uterus, so implantation of a fertilized egg cannot occur. This type of IUD must be replaced every 5 years.

How Effective Is the IUD?

The IUD is 98-99% effective.

How Is an IUD Used?

Once the IUD has been inserted by your doctor, you do not need to take any further steps to prevent pregnancy until it is time to replace it. How long it lasts depends on the type of IUD you receive.

Are There Side Effects Associated With IUDs?

IUDs rarely cause serious side effects when used in a monogamous relationship (having only one sex partner). Side effects include pelvic inflammatory disease, painful and heavy periods, backaches and headaches. Discuss these side effects with your doctor.

Mirena is associated with lighter menstrual periods.

Do IUDs Protect Against Sexually Transmitted Diseases?

No. IUDs do not protect against STDs, including HIV (the virus that causes AIDS). The male condom provides the best protection from most STDs.