Contraception: intra-uterine device (IUD)

What is an intra-uterine device (IUD)?

An intra-uterine device (IUD) – also known as intrauterine contraceptive device (IUCD) – is a small T-shaped plastic device that is inserted into the womb (uterus) to prevent pregnancy. A nylon thread is attached to the end of it so that it can be removed easily.

IUDs currently available in Australia include copper IUDs, which have copper wire bound around the vertical stem, and Mirena, which releases a synthetic progesterone called levonorgestrel.

IUDs are a long-term, reversible form of contraception.

How does the IUD work?

Copper IUDs work by changing conditions in the uterus, which affects the movement of both the sperm and egg, as well as reducing their viability. In addition, the IUD changes the lining of the uterus, making it less suitable for a pregnancy.

Mirena works by secreting levonorgestrel, a synthetic progesterone which is also used in the progesterone-only pill and some combined contraceptive pills. Progesterones thicken the mucus in the uterus and at the cervix, which inhibits sperm movement and prevents sperm from entering the uterus. Mirena also changes the lining of the uterus, making it less suitable for a pregnancy, and can stop ovulation (the release of an egg from the ovaries) in some women.

How effective are IUDs?

IUDs are more than 99 per cent effective in preventing pregnancy. So, less than one woman in every 100 using an IUD will become pregnant in a year.


The advantages of using IUDs for contraception are that they:

  • are very effective at preventing pregnancy;
  • allow fertility to return immediately upon removal;
  • do not interfere with sexual intercourse;
  • can be used while breast feeding;
  • are a long-term option for contraception;
  • are relatively inexpensive; and
  • require minimal ongoing attention.

An additional advantage of Mirena is that it can help reduce heavy menstrual bleeding, and many women experience no vaginal bleeding after 12 months of use.


The disadvantages of using IUDs for contraception is that they:

  • do not help protect against sexually transmitted infections (STIs);
  • may be difficult to insert in women who have not given birth vaginally;
  • may increase the short-term risk of pelvic infection following insertion;
  • if a pregnancy should occur (which is rare), there is an increased risk that it will be in the fallopian tubes (ectopic pregnancy);
  • may perforate the uterus, although this is infrequent; and
  • may be expelled (fall out) undetected.

IUDs may not be suitable for women with multiple sex partners if there is an increased risk of acquiring a sexually transmitted infection, as this may result in pelvic inflammatory disease, which in turn may result in infertility. Similarly, those with a history of recurrent pelvic inflammatory disease or an ectopic pregnancy should discuss with their doctor the suitability of using an IUD.

How are IUDs used?

The device comes with an insertion tube that your doctor will use to place the IUD into your uterus. This is usually done between the last days of your period and the first few days following it, in order to reduce the risk of an undetected pregnancy.

Inserting an IUD is a procedure that takes about 15 minutes. Your doctor may apply a local anaesthetic to your cervix before inserting the IUD. Some women experience some pain or discomfort during insertion.

It’s recommended that you avoid vaginal sex, using tampons, swimming and baths for at least 2 days following the insertion of the IUD.

It is recommended that every month after your period, you check that the string is able to be felt, to ensure that the device has not been expelled without you noticing.

IUDs should be replaced every 3 to 5 years, depending on the type of IUD.

Side effects

For a few days after the insertion of an IUD, you may experience some cramping, pelvic pain and vaginal bleeding.

Copper IUDs

Copper IUDs may cause periods to be heavier, longer and more painful than before, although this usually settles after a few months.


Side effects associated with use of Mirena include:

  • erratic bleeding and spotting (especially in the first 3 to 5 months after insertion);
  • breast tenderness;
  • acne;
  • weight gain;
  • headaches;
  • nausea; and
  • mood changes.

These side effects are more common immediately after insertion, and usually improve over time.

Last Reviewed: 3 September 2013


1. Family Planning NSW. The copper IUD (updated May 2013). (accessed Aug 2013).
2. Family Planning NSW. The hormone-releasing IUD (Mirena)(updated May 2013). (accessed Aug 2013).
3. Other hormonal contraceptive devices (revised June 2009; amended October 2009). In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2013 Jul. (accessed Aug 2013).
4. Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Intrauterine contraceptive devices and infection (updated Jul 2010). (accessed Aug 2013).
5. Family Planning Victoria. The IUD (updated Jan 2010). (accessed Aug 2013).


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