Looking like a letter T, the intrauterine device (IUD), also known as 'the coil' or 'copper coil', is made from plastic and copper wire and is fitted into the uterus by a doctor or nurse.
It releases copper which kills sperm and thickens mucus in the cervix, which makes it hard for sperm to pass through and fertilise an egg. The womb also becomes thinner, which means if an egg were to fertilise, it couldn't attach itself to the womb.
Extremely convenient as it works for 5-10 years. Hormone free so there are few physical side effects and it doesn't affect fertility once its removed. It's also effective, working over 99% of the time.
It can be uncomfortable when first fitted and heavy or painful periods are possible in the first few months while spotting may continue. There is also a risk of pelvic infections. It doesn't protect against sexually transmitted infections (STIs) so to have safe sex, you will still need to use condoms.
Most women but if you have an untreated sexually transmitted infection (STI) or pelvic infection, womb problems, an artificial heart valve, bleed between sex or have had an ectopic pregnancy seek medical advice as it may not be for you. If you're over 40, it can be left in until the menopause.
Last updated August 1, 2018