Ananova:

The US has approved the use of an abortion pill which its supporters say could transform abortions in the country by making them more accessible and more private.

The RU-486 pill, first used in France, has already been used by millions of women in 13 other countries and could be available in the US within a month.

But RU-486, known by its chemical name mifepristone, is only effective in the first stages of pregnancy - within 49 days of the beginning of the woman's last period.

To ensure the pill is used accurately and safely, the Food and Drug Administration which approved the use of the pill in the US, says women must be given brochures called "MedGuides" explaining who is eligible for a pill-caused abortion and what side effects to expect.

They must also make three trips to the doctor to carry out the procedure, which involves taking three of the pills and a second drug, misoprostol two days later which causes uterine contractions to expel the embryo. The woman must then return to the doctor two weeks later to make sure the abortion is complete.

The FDA will allow mifepristone to be distributed only to doctors trained to accurately diagnose the duration of pregnancy and to detect ectopic, or tubal, pregnancies, because those women cannot receive mifepristone.

Studies show mifepristone is 92% to 95% effective in causing early abortion, by blocking action of a hormone essential for maintaining pregnancy. Without that hormone, progesterone, the uterine lining thins so an embryo cannot remain implanted and grow.

The pill-induced abortion can be painful, causing bleeding and nausea. Heavy bleeding is a potentially serious side effect but one the FDA determined is rare. In safety testing of the first 2,100 American women who took mifepristone, four bled enough to need a transfusion.