An IUD is used to prevent pregnancy. You can get copper IUDs or hormonal IUDs (Mirena). These sit inside your uterus (womb). Nylon threads attached to the IUD hang down into your vagina.
An IUD works by preventing fertilisation of the egg. The copper or hormone stops sperm moving through the uterus towards the egg. Occasionally this doesn’t work and an egg is fertilised. The IUD then stops this egg implanting into the uterus.
- The copper IUD is 99 percent effective in preventing pregnancy. Only one woman out of 100 will get pregnant each year.
- Mirena is 99.5 percent effective in preventing pregnancy.
Most women are able to use an IUD including young women and women who have not had children.
Mirena is particularly suitable for women with heavy periods.
Advantages of an IUD
- It can stay in place for 5 years or more.
- It’s possible to get pregnant as soon as the IUD is removed.
- It doesn’t interfere with sexual intercourse.
- The IUD is safe to use if you’re breastfeeding.
- It’s safe to use if you can’t take the pill.
- With Mirena, most women have lighter periods and less period pain. Some women may have no periods at all.
- The copper IUD has no hormonal side-effects.
Disadvantages of an IUD
- You have to have the IUD inserted. This is usually a simple, safe procedure carried out by a doctor or nurse who is experienced at inserting IUDs. It takes about five to 10 minutes.
- Most women have some period-like cramping. Some women feel pain and occasionally feel faint when the IUD is put in or taken out.
There are some risks from having an IUD put in:
- there may be a small chance of infection (about 1%) when an IUD is put in
- there is a very small risk of damage or perforation of the womb (about 1 in 1,000)
- you may get pregnant with an IUD in place but this is rare
- any pregnancy can be ectopic (in the tubes). This risk is less than in women not using any contraception
- a Copper IUD may cause more bleeding and cramping during periods
- the copper can very rarely cause an allergic reaction
- the IUD can occasionally come out by itself (about 5%). You can check the strings are still in place after each period or at the beginning of each month.
- Mirena may initially cause irregular, light bleeding for more days than usual
- Search the Medsafe website for more information about Mirena's side effects.
Getting an IUD
If you decide that an IUD is the right contraception for you, you’ll need to see your doctor or a Family Planning clinic.
The IUD is put into your uterus through your cervix. The procedure takes a few minutes and may be painful.
- Following the placement of an IUD into the uterus, you may have some cramps for a couple of hours and some spotting, which could last for up to 2 weeks. You may also have heavy periods. This is not as common with the hormone type of IUD (Mirena).
- To reduce the risk of infection after the insertion, you should use sanitary pads (not tampons) for the first 48 hours, and do not have sex in that time.
The best time to fit an IUD is:
- during or just after a menstrual period
- 6 weeks after your baby is born
- immediately after an abortion.
An IUD can also be used as an emergency contraception method after unprotected sex.
As a safety precaution, after every period you should check for the string attached to your IUD, to make sure it’s still properly in place. It’s also a good idea to do this one week after your IUD has been put in.
When to see your doctor
If you have an IUD, you should see your doctor if you have any of these symptoms:
- severe cramping
- unusual bleeding
- fever without another cause
- bad-smelling discharge
- late period.
You should also see your doctor if you can feel the hard plastic of the IUD or if you can’t feel the string.
Call Healthline 0800 611 116 if you are unsure what you should do.
Removing your IUD
If you think you might be pregnant, see your doctor to get your IUD removed as soon as possible. There’s an increased chance of miscarriage if the IUD is left in place while you’re pregnant.
If you decide you want your IUD removed, the best time is during your period. Your doctor removes the IUD by pulling the threads. This may be painful for a few seconds.
For more information, contact your doctor or Family Planning.