The intrauterine device (IUD) is a method for women who have already had children.It is a small plastic device inserted into the uterus (womb). It may contain copper or secrete hormones. The mechanism by which it prevents pregnancy is not completely understood.

Advantages:

• Once it's inserted, you don't have to do anything.
• More than 99% effective.
• Good for up to 10 years.
• Very economical if used the whole 10 years.
• Independent of partner cooperation.

Disadvantages:

• High initial cost (up to $500).
• Menstrual periods may be longer, heavier and/or more uncomfortable.
• Complications of some sexually transmitted diseases are more likely. They should only be used by women in reliably monogamous relationships.