The intrauterine device Intrauterine devices, or IUDs, are a long-term method of birth control. This fpa factsheet explains how they works, the pros and cons and whether this method is suitable for you.

In this article

What is it? How does it work?

How reliable is it? Can anyone use an IUD?

Where can I get an IUD?

The intrauterine contraceptive device, or IUD, is a small plastic or copper device that's put into the womb. There are many different types, which are effective for three to ten years depending on type. The IUD is a long-acting reversible method of contraception.

The main way is to stop sperm reaching an egg. An IUD does this by preventing sperm from surviving in the cervix, womb or fallopian tube. It may also work by stopping a fertilised egg from implanting in the womb. An IUD does not cause an abortion.

Myth: The IUD causes infection and makes you infertile
Fact: Not true - having unprotected sex with someone who has an infection causes infection, but the IUD doesn't cause infection or make you infertile
Myth: Young women cannot use the IUD
Fact: Not true - most women of any age can use the IUD

It's about 99 per cent effective, depending on which IUD is used. This means, using this method, on average fewer than one to two women in 100 will get pregnant in a year.

Newer IUDs contain more copper and are the most effective. They're more than 99 per cent effective. All long-acting reversible methods of contraception are very effective because while they are being used you dont' have to remember to take or use contraception.

How is it used?

The IUD can be fitted at any time in your menstrual cycle if you're certain you're not pregnant. It will be effective immediately. Sometimes your doctor or nurse will check for any possible existing infection. This will be done before the IUD is fitted.

In some circumstances, antibiotics may be given at the same time as fitting the IUD.

The IUD has two soft threads at one end, which hang through the cervix into the top of the vagina. These are so you can check the IUD is in position. You should check after fitting and then about once a month.

Advantages:

• It works as soon as it is put in
• It works for three to ten years depending on type
• It doesn’t interrupt sex
• It can be used if you're breastfeeding
• Your normal fertility returns as soon as the IUD is removed
• It's not affected by other medicines

Disadvantages:

• Your periods may be longer, heavier or more painful - this may improve after a few months
• You'll need an internal examination to check if it's suitable, and when it is fitted
• There is a very small chance of infection in the first 20 days after the IUD is put in
• The IUD may come out (expulsion) or it may move (displacement) - this is more likely to happen shortly after it has been put in
• The IUD may go through (perforate) the cervix or womb when it's put in, but the risk is low when it's put in by an experienced doctor or nurse
• If you do become pregnant, there is a small increased risk of you having an ectopic pregnancy (a pregnancy occurring outside the womb, normally in the fallopian tube). This risk is less than in women using no contraception

Most women can do so, but it may be unsuitable if you:

• Think you might already be pregnant
• Have an untreated sexually transmitted infection (STI) or pelvic infection
• If you and your partner are at risk of getting an STI
• Have problems with your cervix or womb
• Have unexplained bleeding from your vagina (for example, between periods or after sex)

Other things to consider

Young women or women who've never been pregnant can use the IUD. Once it has been fitted, you can forget about it until it needs replacing.

Women with HIV can use an IUD.

It doesn't protect you against STIs.

IUDs are free on the NHS from contraception clinics, sexual health clinics or general practice.

Intrauterine system

A new type of IUD has been introduced in recent years. This small T-shaped plastic device contains a progestogen hormone (similar to the natural progesterone that women produce in their ovaries) which it slowly releases. Because it works as a contraceptive in two ways, both as an IUD and through this hormonal effect, it's known in the UK as an intrauterine system or IUS (rather than an IUD). Read the Intrauterine system article for more information.

Advice and support

Call fpa's helpline on 0845 122 8690.

This article was last reviewed in July 2007.