Youre heard of the morning-after-pilland probably heard that its not fool-proof at preventing pregnancy. But another method is! If youve had sex without protection and need to be certain that you wont have to live with an unintended pregnancy, you may consider having a doctor insert an intra-uterine device, or IUD, into your uterus. This method is literally 99.9 percent effective when the IUD is inserted within 5 days after unprotected sex. An IUD is a T-shaped, plastic device that can be put into the uterus to prevent a pregnancy. ParaGardthe type used for this purposecan prevent a pregnancy by encouraging the body to release leukocytes and prostaglandins, substances hostile to both sperm and eggs. The device can also stop an egg that has already been fertilized from implanting into the uterus. This type of IUD can stay in place and remain effective as birth control for 12 years, or it can be removed after the next menstrual period. A final note about IUDs: They are not recommended for women at a high risk for STDs following their sexual encounter. If this is you, talk to your doctor about other options.