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Intrauterine Contraception (IUD)

An IUD (intrauterine device) is a small T-shaped piece of plastic or metal that a health care provider places in a woman’s uterus to prevent pregnancy. Plastic strings tied to the end of the IUD hang down through the opening of the uterus (cervix) into the vagina. These strings are not visible on the outside of a woman’s vagina.

As with other forms of birth control, IUDs do not protect from STDs (sexually transmitted diseases).

Types of IUDs

There are two types of IUDs that are approved in the United States:

ParaGard IUD (Copper):

  • Mechanism of action: the copper acts as a spermicide making the sperm unable to move or reach an egg.
  • Length of use: The copper IUD is approved for use for 10 years.
  • Effects on menstrual cycle: Because this is a nonhormonal form of contraception, women using the copper IUD will continue to have menses similar to before initiating the IUD. Twenty percent of users will complain of heavier periods and/or more painful cramps; this usually improves with time.

Mirena IUD (levonorgestrel):

  • Mechanism of action: The Mirena IUD releases a progestin hormone which helps to thicken the cervical mucus to prevent sperm from reaching an egg. It also helps to decrease ovulation in some cycles.
  • Length of use: The Mirena IUD is approved for use for five years.
  • Effects on menstrual cycle: At least half of users will report light periods. Twenty percent of users will say they no longer have periods. It is common, however, during the first three to six months of use to have irregular bleeding in the form of daily spotting.

Safety and effectiveness of IUDs

IUDs are safe and very effective in preventing pregnancy, with less than 1 percent of women using the device becoming pregnant. IUDs provide women extended pregnancy protection without the hassle of taking daily pills (which can fail when taken inconsistently), or other contraceptive options that must be maintained regularly (such as vaginal rings, birth control shots or hormonal implants). Once an IUD is in, it works as a very effective form of contraception.

All medications carry risk, so it’s important to discuss birth control options with your medical health professional.

Benefits of IUDs for contraception

Once the IUD has been inserted, protection can last up to 10 years, depending on the type of IUD, and there is no daily pill or activity to remember before sex.

The ParaGard IUD does not affect a woman’s hormone levels. The Mirena IUD also reduces menstrual cramping and bleeding. All IUDs can be safely used during breastfeeding.

Once the IUD has been removed, the ability to become pregnant returns quickly.

The ParaGard IUD can also be used as emergency birth control to prevent pregnancy after unprotected sex. If inserted within five days after unprotected sex, it can help reduce the risk of pregnancy by 99.9 percent.

Risks of IUD birth control

On rare occasions, an IUD can come out without the woman noticing, increasing the risk of a woman becoming pregnant during intercourse. Do not use an IUD if you:

  • Think you might be pregnant.
  • Have had a pelvic infection following childbirth, miscarriage or abortion within the last three months.
  • Have unexplained bleeding in your vagina.
  • Have a uterine perforation during IUD insertion.
  • Have pelvic tuberculosis.
  • Have cervical cancer that hasn’t been treated.
  • Have uterine cancer.

Do not use the ParaGard IUD if you have an allergy to copper, Wilson’s disease or an inherited disease that blocks the body’s ability to get rid of copper.