A small plastic and copper device that is fitted into your womb. It has one or two soft threads on the end. These thin threads come through the opening at the neck of your womb (cervix) into the top of your vagina.

HOW IT WORKS Stops sperm from reaching an egg. It may also make the egg move more slowly along the fallopian tube and/or stop the egg from settling in the womb.

PROTECTION Immediately upon insertion, lasting three to ten years, depending on type (although you can have it removed earlier).

BABY-PROOFING ABILITIES 99 percent.

STD-PROTECTION None.

SIDE EFFECTS YOU NEED TO KNOW ABOUT Periods may be heavier, longer or more painful. You may have some slight bleeding between your first two or three periods after you have had the IUD fitted. There is also a possibility of you getting an infection during the first 20 days after an IUD is put in. If you feel unwell and have any pain in your lower abdomen, with a high temperature or a smelly discharge from your vagina in the first three weeks after the IUD is fitted, see a doctor as soon as possible. You may have an infection.

CAN IT RUIN THE MOMENT? No.

HASSLE FACTOR Medium. You need to look for the IUD threads monthly, since they can be pushed out by your womb or can move. This is more likely soon after the IUD has been put in, and you may not know this has happened. You will also need to have your IUD checked four to six weeks after it is put in, and then once a year.