The Food and Drug Administration has approved changes to the label for mifepristone, also known as "the abortion pill," the agency said this week.

The new label says that the drug (sold under the brand name Mifeprex) can be taken later in pregnancy and at a lower dose than what was recommended on the old label. Many doctors already follow the new regimen in what's known as "off-label" use, because recent studies have shown that this regimen is safer and more effective than the protocol on the old label. But a few states, including Ohio, Texas and North Dakota, had laws that required doctors to follow the regimen on the label exactly.

"These laws compelled health care providers to use an outdated, inferior and less effective regimen," Planned Parenthood said in a statement, weighing in on the FDA's new rule. "The FDA's approval of the new Mifeprex label means that medication abortion [using drugs to end a pregnancy] can once again be provided everywhere in the U.S. in accordance with what research shows is safest and most effective," the statement said. [11 Big Fat Pregnancy Myths]

Here are the facts about mifepristone:

What is mifepristone?

Mifepristone is a medication used to induce abortion. It's taken in combination with another drug, called misoprostol, to end a pregnancy early on. The drug combination is an alternative to the surgical abortion procedure performed in a clinic, called an aspiration abortion..

How does it work?

Mifepristone blocks the action of the hormone progesterone, which is important to maintain a pregnancy. Blocking progesterone causes the lining of the uterus to break down, and ends the pregnancy, according to Planned Parenthood.

What changes did the FDA make to the mifepristone label?

The old label said that mifepristone could be taken up to 49 days after a woman's last menstrual period, but the new label says that the drug can also be taken later in pregnancy: up to 70 days after a woman's last period. The new label also lowers the dose of the medication, from 600 milligrams to 200 mg. This regimen reduces the side effects, and also the cost, of a medication abortion, according to the American College of Obstetricians and Gynecologists.

Finally, the new label reduces the number of appointments that a woman needs for a medication abortion from three to two. The old label said that in addition to the initial appointment needed to get a prescription for the medication, women needed to return to the doctor three days after taking mifepristone, and again 14 days after taking the drug. But the new label eliminates the appointment after three days, and says that a woman should return for follow-up with her health care provider seven to 14 days after taking the medication.

Is mifepristone the same as the morning-after pill?

No, the morning-after pill, also called emergency contraception, is taken to prevent pregnancy from occurring a short time after unprotected sex; it does not affect an established pregnancy.

What are the risks?

Common side effects of a medication abortion include nausea, weakness, fever/chills, vomiting, headache, diarrhea and dizziness, according to the FDA. Serious side effects are rare, but can include infection and hemorrhage; these occur in less than 0.5 percent of people who take the medication, the FDA said.

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