Emergency contraception, also known as the morning after pill, is a pill available to prevent pregnancy after unprotected sex. There are two types of emergency contraception pills, one containing both estrogen and progestin and the other a progestin-only pill. Levonorgestrel/ethinyl estradiol is more effective than Preven and has few side effects associated with it. The copper IUD, which must be inserted by a medical professional within 5 days of unprotected sex, can prevent the implantation of a fertilized egg. Approximately 80% of women keep the IUD inserted as birth control for up to 10 years.