An intrauterine device (IUD) has 2 thin threads that hang down a little way from your womb into the top of your vagina. The doctor that fits your IUD will teach you how to feel for these threads and check that it's still in place.
Check your IUD is in place a few times in the first month and then after each period, or at regular intervals.
It's very unlikely that your IUD will come out, but if you cannot feel the threads or think it's moved, you may not be protected against pregnancy. See your doctor straight away and use additional contraception, such as condoms, until your IUD has been checked. If you have had sex in the last seven days, you should use a morning after pill.