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Intra-uterine Device (IUD) / Intra-uterine System (IUS)

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What is the Intra-uterine device (IUD)?

The (IUD) is a small, T-shaped frame with thin copper wire wrapped around it. It fits inside the uterus.

What is the Intra-uterine System (IUS)?

The IUS is a small, T-shaped frame wrapped with a hormone. It fits inside the uterus and releases a small amount of progestin-like hormone. Both IUD and IUS have thin plastic strings attached, which hang through the cervix into the vagina. The strings can be trimmed if they bother your partner. Both the IUD and IUS must be put in and removed by a health care provider.

How do the IUD and IUS work?

The copper IUD may work by changing the chemistry in the uterus, destroying sperm or preventing a fertilized egg from growing or attaching to the uterus.

The IUS slowly releases the hormone that acts to thin the lining of the uterus and thicken the cervical mucus to make it harder for sperm to enter the uterus.

How effective is the IUD/IUS?

The IUD/IUS are very effective methods of birth control. Less than 1 in 100 women get pregnant each year.

The IUD/IUS does not protect you from sexually transmitted infections (STIs) - always use a barrier such as condom.

What are the advantages of the IUD/IUS?

  • The IUD/IUS stays in place and is effective for up to five (5) years.
  • The IUS does not contain estrogen, so it is useful for women who have sensitivity to estrogen.
  • The IUD/IUS decreases the amount of menstrual bleeding and may decrease menstrual cramping.
  • It is low cost after the initial purchase.
  • The IUD/IUS may lead to less menstrual bleeding and in some cases periods stop altogether.
  • The IUD may be used by women who are unable to use hormonal methods of birth control.
  • There is no need to interrupt sex to use it.
  • The IUD/IUS does not increase risk of infertility.  When taken out, women will get pregnant at the same rate as those who never used an IUD/IUS.

What are the side effects and disadvantages of the IUD/IUS?

  • The IUD/IUS does not protect against STIs. Always use a barrier such as condoms for protection.
  • Irregular spotting or bleeding is common for the first 3-6 months after insertion. It usually improves with time.
  • Cramping or backache may occur for a few days
  • The IUD may trigger longer and heavier periods with more cramps that may decrease with time.
  • The IUD/IUS must be inserted and removed by a health care provider
  • The initial cost may be $500-$1000
  • Sometimes the IUD/IUS can slip out of the uterus
  • Rarely a woman could develop an infection

Can anyone use an IUD/IUS?

An IUD is not recommended if:

  • There is a chance you are pregnant.
  • You have pelvic inflammatory disease (PID) or an infection in your uterus, ovaries or fallopian tubes.
  • You are at risk for STIs (if you have more than one partner).

What else do I need to know?

It is important to tell your health care provider immediately if:

  • You find the length of string to be longer or shorter than when inserted
  • You are not able to feel the strings
  • Have severe abdominal cramping
  • Have pain or bleeding during sex
  • Have unexplained vaginal bleeding
  • Have unusual vaginal discharge
  • Have flu-like symptoms
  • You have changes in your menstrual cycle (missed, late, or unusually light)


Society of Obstetricians and Gynecologists

Planned Parenthood

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Page Last Modified: Wednesday, 15 April 2015.