An intrauterine system (IUS, not to be confused with the IUD) is a small, T-shaped plastic device that contains progestogen (a hormone). The IUS is clever and works in a number of different ways. Firstly, the hormone thickens the mucus in the neck of the womb which makes it very difficult for sperm to get past. Secondly the hormone can also stop an egg being released from the ovary. Finally, the IUS prevents a fertilised egg implanting itself properly into the womb where it can grow into a baby.
Like many other contraceptive methods, the IUS offers no protection against sexually transmitted infections.
It lasts for up to 5 years or until it is removed.
Once it is removed your fertility will return and you could get pregnant.
The IUS is more than 99% effective. This means that fewer than one in every 100 women who use the IUS will get pregnant in a year.
It needs to be fitted by a trained doctor or nurse at your GP surgery or sexual health clinic.