A law in Arizona that the ACLU is calling "the most extreme and dangerous of abortion bans" was blocked from taking effect on Thursday after an emergency appeals request.

Arizona was set to become the ninth state to forbid doctors from aborting a fetus 20 weeks into a pregnancy. But unlike elsewhere in the country, Arizona would start the 20-week count after a pregnant woman's last menstrual period, or about 18 weeks into a pregnancy -- which is typically before medical problems can be detected in fetuses in prenatal exams, according to a lawsuit filed by the ACLU and the New York-based Center for Reproductive Rights.

The law, which the U.S. 9th Circuit Court of Appeals blocked Wednesday, will likely be on hold through at least October, when all briefs on the case will be filed, said Julie Rikelman, litigation director for the Center for Reproductive Rights. A final decision is likely to be made in November or December, she said.

"We're thrilled with the decision," Rikelman said. "It's really great news for women in Arizona. We're very excited that women will still be able to get the health care that they need."

Under the ban, signed into law in April by Gov. Jan Brewer, R-Ariz., physicians could have their licenses revoked and face jail time if they violate its terms. Exceptions are life-threatening situations or medical emergencies for the mother, which Arizona law defines as a "serious risk of substantial and irreversible impairment of a major bodily function."

Those exceptions were not enough for The Center for Reproductive Rights and the American Civil Liberties Union, who filed an emergency appeal Monday night after a preliminary injunction they filed in federal court in Phoenix was dismissed.

"This is by far the narrowest health exception in any abortion law in the country," Alexa Kolbi-Molinas, staff attorney at the ACLU's Reproductive Freedom Project, said. "It would force a physician who was caring for a woman with a high-risk pregnancy to wait until her condition has deteriorated to the point that it poses an immediate threat of death or major medical damage before offering her the care she needs."

It would also affect expectant mothers who receive disconcerting diagnoses about their fetuses: news that their child won't survive after birth, or will only survive for a short period of time in excruciating pain.

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"For a lot of these women, that diagnosis can't be made until after 20 weeks," Kolbi-Molinas said. "This certainly is the most extreme and dangerous of abortion bans that we've seen in some time."

Arizona's late-term ban is the latest in a string of anti-abortion measures being implemented across the country. Alabama, Idaho, Indiana, Kansas, Oklahoma, Georgia, Louisiana, and Nebraska have passed similar restrictions in recent years; North Carolina enacted its own ban, with different specifications to its law, decades ago, said Elizabeth Nash, state issues manager with the Guttmacher Institute, a rights organization based in New York.

A 'tidal wave of abortion restrictions' across the U.S.

Nash said there's been "a tidal wave of abortion restrictions" passed recently: Prior to 2011, the most restrictions ever to be passed in a year on the state level was 34, in 2005. But in 2011, a record 92 abortion restrictions were passed, followed by 39 so far in 2012, she said.

Anti-abortion groups are pleased with their recent success in enacting restrictions, particularly the bans on late-term abortions.

"It's a fetal pain law, and it's one of many that have passed in the last few years. We're very pleased," Jeanne Monahan, director of the Center for Human Dignity at the D.C.-based Family Research Council, said. "This is a law that has to do with the fact that a developing baby can feel pain at a certain time in development and so because of that, abortions are not legal after that period in its development."

Millions of women will no longer have to pay for birth control pills, Pap smears or mammograms and they will also have the right to breast feeding supplies and domestic violence screening. NBC's Kelly O'Donnell reports.

Monahan lauded other recent anti-abortion wins on the state level -- parental consent and informed consent among them.

"Anything that can make abortion more rare, I think most people will agree upon," she said, citing a Gallup poll from May, which found the percentage of Americans who call themselves "pro-choice" is at a record low of 41 percent.

According to the Guttmacher Institute, the increase in these laws is due to a shift in political makeup: state governments becoming more conservative over the past decade, particularly since the midterm elections.

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"When the November 2010 elections came about, state legislatures and some governorships moved substantially to the more conservative end," Nash said. "You really had this welcoming environment to adopt abortion restrictions."

In Arizona, the change has been dramatic.

"If we look to 2000, Arizona was classified as a pro-choice state, supportive of abortion rights. For many years, the legislature was fairly hostile to abortion, but there was a governor in place who would veto abortion restrictions," Nash said. "When Gov. [Janet] Napolitano left for the federal government in 2009, Jan Brewer took over."

The state has passed at least a dozen abortion restrictions in the three years since Brewer became governor, Nash said.

Kolbi-Molinas, the ACLU lawyer, said the Arizona ban could put women in a position where they feel pressure to get an abortion when they might not otherwise.

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"One of the perverse effects of this law, if it does go into effect, is there are some women who have high-risk pregnancies ... and they may not be able to carry to term, but they really want to try as long as they can," she said. "They would feel pressured to get an abortion before 20 weeks because they wouldn't know if they'd be able to protect their health afterwards."

Up to 90 percent of abortions occur within the first trimester, she added, making the number of women who would even consider getting abortions after 20 weeks only a tiny sliver for Arizona to have to worry about.

"Another thing worth noting is the majority of women who have abortions are already mothers," she said. "If you think about the way this law is putting women at risk if there's something wrong with their health, it's essentially denying them the abortion they might need to return home to their family."

Despite the dozens of restrictions placed on abortion in recent years, anti-abortion advocates aren't gloating.

"In January, we're going to be marking the 40-year anniversary of Roe v. Wade, and approximately 54 million abortions have occurred since that decision in 1973," Monahan, of the Family Research Council, said. "I don't think it's a moment of victory. It's a somber moment in our country on a lot of levels."

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