When this drug appeared, it really produced a sexual revolution. Contraceptive pills are good, but they do pose some hampering issues, like the fact the woman has to take them constantly in a scheduled way. But mifepristone meant total sexual freedom, as it did not require all this, and could be the solution after an "accidental" night of free sex.

Mifepristone, the "abortion pill" known as RU-486, could turn now into a new form of daily contraceptive. The normal contraceptive pills contain estrogen and progesterone, but estrogen is known as a main risk factor of breast cancer, while progesterone-only pills often induce irregular bleeding and spotting.

RU-486 (from the French company that first developed the chemical, Roussel Uclaf) is a synthetic steroid chemical effective as an abortifacient in the first two months of pregnancy, and in smaller doses - for its known effect - an emergency contraceptive.

The synthetic steroid blocks ovulation through a different mechanism than that of the female sex hormones, estrogens and progesteron.

A team led by David Baird at the University of Edinburgh, UK, gave 72 women a low daily dose of mifepristone or the progesterone-only pill for 24 weeks. Both pills were similarly effective at preventing pregnancy, but mifepristone induced significantly less unwanted bleeding.

RU-486 was first available in France, and in many countries it's commercialized under the name Mifegyne, while in the US it is sold as Mifeprex.

Still, there is a vivid controversy around mifepristone. Nearly all women who took it in clinical trials accused abdominal pain, uterine cramping, and vaginal bleeding or spotting for an average of 9-16 days. Other less common side effects were nausea, vomiting, diarrhea, dizziness, fatigue, fever and even pelvic inflammatory disease (PID), a serious complication.

Mifepristone is also not recommended in case of ectopic pregnancy, adrenal failure, hemorrhagic disorders, inherited porphyria, anticoagulant or long-term corticosteroid therapy, smokers, and over 35-year-old women.