An IUD is put in a woman's uterus by her doctor. It isn't known exactly how IUDs prevent pregnancy. They seem to stop sperm from reaching the egg or prevent the egg from attaching to the uterus. Some IUDs used in the past were related to serious health problems. Today IUDs are safer but they still have some risks.
Most doctors prefer to reserve IUDs for women who have already had a baby.
The most common side effects of IUDs include heavier bleeding and stronger cramps during periods. A benefit of using an IUD is that you don't have to think about birth control every day. Sterilization is when a man or woman has an operation to permanently prevent pregnancy. If you're sure that you don't want to have children or don't want more children, sterilization is a good choice. The fallopian tubes are what the eggs travel through to reach the uterus.