An intrauterine device or an IUD is a small, plastic, T-shaped device with a string attached to the end .The IUD is placed inside the uterus to prevent pregnancy. Once in place, the IUD stays in your uterus until doctor removes it. The IUD prevents sperm from joining with an egg. It does this by making the sperm unable to go into the egg and by changing the lining of the uterus. There are 2 types of IUDs: a copper IUD and a hormonal IUD. The copper IUD releases copper particles to prevent pregnancy, while the hormonal IUD releases the hormone progestin to prevent pregnancy. Usually you may have cramps and a backache for the first few hours after an IUD is inserted into your uterus. Some women have bleeding and pain for a couple of weeks after the IUD is inserted. You may experience heavier period if you are using the copper IUD. Rarely, the uterus can be injured when the IUD is put inside and also may have pelvic infections and problems getting pregnant after removal. These problems are very rare. The IUD does not protect you from any sexually transmitted infections (STIs). In addition, the more people you have sex with, the greater your chance of getting an STI. The IUD alone is best for women who have only one long-term sex partner. In addition, you shouldn't use the IUD if you're pregnant, if you have abnormal bleeding or if you have cancer of the cervix or uterus. You should not use the copper IUD if you are allergic to copper. The copper IUD can remain in your body as long as 10 years. The hormonal IUD needs to be replaced every 5 years.