image Unintended pregnancy is surprisingly common. At least half of all pregnancies in the United States each year are mistimed or unplanned, because birth control measures were not used or those that were used did not work. An emergency contraceptive pill is available to provide women with another option for preventing unintended pregnancy

There are many options for birth control, but there are also products that have been developed specifically for use only in an emergency.

Emergency contraceptive pills prevent pregnancy in a variety of ways. Depending on the time of the month in a woman's cycle, the drug may prevent ovulation (release of the egg from the ovary), interfere with fertilization, or prevent a fertilized egg from attaching in the uterus. They will not induce an abortion if a woman is already pregnant, according to the definition of pregnancy used by the National Institutes of Health and the American Congress of Obstetricians and Gynecologists.