An intrauterine device (IUD) is a highly effective and reliable method of contraception that lasts for 5 years or more.
What is the intrauterine device (IUD)?
IUDs are small devices that are placed inside your uterus (womb) to prevent pregnancy.
Types of IUD
There are 2 types of IUD:
- the hormonal IUD - made of plastic and which releases a hormone
- the copper IUD - made of copper and plastic, which does not release a hormone.
The only hormone-releasing IUD available in Australia is Mirena, which slowly releases a progestogen hormone called levonorgestrel.
There are 2 copper IUDs available in Australia. Multiload lasts for up to 5 years and the Copper T (or TT380R) lasts for up to 10 years.
How does the IUD work?
The hormonal IUD releases progestogen which:
- thickens the mucus at the entrance to your uterus so sperm can't get through
- thins the lining of the uterus, making it hard for a fertilised egg to take hold.
The copper IUD works by:
- making it harder for sperm to reach and fertilise an egg
- changing the lining of the uterus so that if an egg was fertilised, it still wouldn't be able to attach and develop.
Copper is toxic to sperm, so the copper IUD can also be used as an emergency contraceptive within 5 days of unprotected sex.
How well does the IUD work?
The IUD works very well if inserted and used properly, and is one of the most effective reversible methods of contraception available.
If 100 women use an IUD for a year, fewer than 1 will become pregnant.
Advantages and disadvantages of the IUD
Both types of IUD offer several benefits, which include being:
- extremely good at preventing pregnancy
- easy to use and maintain
- long-lasting and cost-effective
- immediately reversible if you decide you want to get pregnant.
The hormonal IUD also makes periods lighter and less painful. Sometimes they stop altogether.
The main disadvantages of IUDs include:
- a small risk of problems after insertion, such as pelvic infection
- they can move out of place
- Mirena can cause side effects such as irregular bleeding and sore breasts
- copper IUDs can initially make periods heavier and more painful.
Although IUDs provide protection for many years, they can be removed earlier. It is a quick procedure, in which a doctor gently pulls on the string, and the IUD's arms fold up so it slips out. Some women find it uncomfortable while others don't feel very much.
Last reviewed: February 2017