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Birth control options: copper IUD

The information on this page describes the conventional copper IUD (intrauterine device). Another form of IUD, called Mirena, is also available in Canada. It is inserted into the uterus like other IUDs, but it also contains a hormone to increase its effect.

IUDs are small devices that fit inside the uterus to prevent pregnancy. IUDs available in Canada are made of copper and plastic and shaped like a T. There are several theories of how they work, but we believe that they prevent sperm from fertilizing an egg. To a lesser degree, they may also prevent a fertilized egg from attaching to the wall of the uterus. If there are no complications, an IUD can be left in place from five to 10 years. They are 99 per cent effective against pregnancy but they do not protect you and your partner against sexually transmitted infections. Women with the following conditions should not use a copper IUD:

  • currently pregnant
  • allergic to copper
  • large fibroids or uterine cancer
  • weakened immune systems
  • heavy periods or severe cramps (this does not apply to Mirena)
  • undiagnosed bleeding from the vagina or undiagnosed pelvic pain
  • have had recent or chronic pelvic infections
  • current vaginal, cervical or pelvic infection
  • women who are at increased risk of sexually transmitted infections

How an IUD is inserted

An IUD must be inserted in a doctor’s office or clinic. It is often inserted during your period because it may be easier to insert, and ensures that you are not pregnant. It can be inserted shortly after giving birth or having an abortion. An IUD may also be used as emergency contraception by inserting it within five to seven days after unprotected intercourse.

The insertion takes about five minutes. It is inserted into the uterus. Thin strings attached to the base of the T hang down through the cervical opening. These strings are trimmed so they are just long enough for you to check that the IUD is in place and so that a health care provider can use them to remove the IUD at a later date. Most women have some cramps when the IUD is being inserted.

You may want to use another method of birth control as back-up for a month in case the IUD moves or comes out. After six weeks, return to your doctor or clinic to check your IUD, then continue to have your regular yearly check-ups. You should check for the IUD strings each month after your period is over.

Call your doctor or clinic if you:

  • cannot feel the strings
  • feel the tip of the IUD protruding when you do your monthly check
  • miss a period or think you may be pregnant
  • have unusual cramping, pain or bleeding
  • have a vaginal discharge that seems different or has a different odour
  • your IUD comes out

The IUD can be easily removed if you wish to get pregnant.


  • very effective
  • copper IUDs are inexpensive
  • can be rapidly reversed if you wish to get pregnant
  • neither partner can feel an IUD during sex
  • the woman controls this method of birth control
  • can remain in place for many years
  • does not cause any hormonal changes in your body
  • can be used during breastfeeding


  • your periods may be longer or heavier with a copper IUD
  • you may have increased cramping with a copper IUD
  • does not protect against sexually transmitted infections
  • if this method fails and pregnancy occurs, it is more likely to be an ectopic pregnancy
  • increased risk of pelvic infection associated with insertion
  • rarely, an IUD may puncture the wall of the uterus

This information is provided by Women’s College Hospital and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: Oct. 29, 2014

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