MORNING AFTER PILLS

[nrkerr]

[b]Emergency contraceptive pills (ECPs) are not to be confused with mifepristone (RU486, Mifeprex), which is used as an "abortion pill".[/b] The term "emergency contraceptive pill" does not refer to mifespristone, which is most commonly used in 200 or 600 mg doses as an abortifacient.[13] However, in China and Russia only,[11] mifepristone is available as either emergency contraception or as an abortifacient, depending on whether it is used before or after implantation. If used as emergency contraception, a low dose of mifepristone is slightly less effective than higher doses, but has fewer side effects.[14] As of 2000, the smallest dose available in the USA was 200 mg.[15] Mifepristone, however, is not approved for emergency contraceptive use in the United States.[16] A review of studies in humans concluded that the contraceptive effects of the 10 mg dose are due to its effects on ovulation,[17] but understanding of its mechanism of action remains incomplete. Higher doses of mifepristone can disrupt implantation and, unlike levonorgestrel, mifepristone can be effective in terminating established pregnancies.

http://en.wikipedia.org/wiki/Emergency_contraception (feel free to read more, I am tired.)