This device has been found to be 99% effective in avoiding pregnancy. IUD's have been found to be good for teens, as they are not good with taking birth control pills or insisting on the use of a condom.
Although IUD's are good at preventing pregnancy, users must be aware of the side effects like headaches, nausea and cramps.
It is also important to know that IUD's cannot protect against transmission of sexually transmitted diseases.
Source: Medindia