The letters "IUD" stand for "intrauterine device." IUDs are small, "T-shaped" contraceptive devices made of flexible plastic that are available by prescription only. IUDs work by preventing sperm from joining with an egg by affecting the way they move. 

IUDs also alter the lining of the uterus. In theory, this may prevent pregnancy by preventing the implantation of a fertilized egg — but this has not been scientifically proven.

IUDs have a string attached that hangs down through the cervix into the vagina. A woman can make sure the IUD is in place by feeling for the string in her vagina. A doctor uses the string to remove the IUD.


The IUD is one of the most effective reversible methods of birth control. Of 100 women who use an IUD, one or fewer will become pregnant during the first year.

It is important to remember that the IUD does not protect against sexually transmitted infections, and in fact, may actually result in a greater infection if a woman is exposed to a STD. Use a condom with the IUD to reduce the risk of infection.

Who is a candidate for the IUD?

According to the American College of Obstetricians & Gynecologists (ACOG) Practice Bulletin, January 2005, the following individuals are candidates for the IUD:

  • Never-pregnant or previously-pregnant women at low risk for sexually transmitted diseases
  • Women who desire long-term contraception that can be easily reversed.
  • An IUD may be the best option for women with the following medical conditions:
  1. Diabetes
  2. Thromboembolism
  3. Menorrhagia/dysmenorrhea
  4. Breastfeeding
  5. Breast cancer
  6. Liver disease

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