When the abortion pill became available in the United States in 2000, 12 years after it was approved in France, activists on both sides of the debate predicted that what was then called RU-486 would revolutionize the abortion landscape. One Planned Parenthood medical director told a journalist in the late 1990s that he expected medication abortions to make up 30 percent of all abortions within three or four years. Anti-abortion leaders, meanwhile, foresaw the procedure’s becoming effectively invisible, and therefore difficult to confront directly. George W. Bush, then the Republican nominee for president, said he feared the new protocol would ‘‘make abortions more and more common.’’

.. In 2014, the number of abortions in the United States dropped below one million for the first time since 1975.

.. A decade after RU-486’s arrival in the United States, fewer than 18 percent of abortions took place via medication

.. Even among women whose pregnancies were eligible for the abortion pill — at the time, eight weeks’ gestation or less — almost three-quarters underwent surgery instead.

.. As public discussion about abortions has focused on surgical abortions, the anti-abortion movement has notched victory after victory, chipping away at abortion access through a constellation of state laws that heavily regulate clinics, starve providers of funds and require women to undergo ‘‘counseling’’ or waiting periods before procuring the procedure. As a result, at least 162 abortion providers closed or stopped offering the service between 2011 and 2016

.. In the Midwest and the South, more than half of all women live in counties with no abortion provider at all.

.. But today, 17 years after RU-486 was approved, medication abortion is approaching its initial promise — or threat, depending on your point of view. American women now end their pregnancies with medication almost as often as they do with surgery

.. The experience of taking a few pills in private is on the cusp of becoming what we mean when we say ‘‘abortion.’’

.. This steady rise of medication abortion, or what the anti-abortion movement calls chemical abortion, presents the movement with a significant challenge, one that has turned out to be more complicated than the fear that abortion would become more common.

.. Medication abortions take place relatively early in pregnancy, and they are eliminating many of the images and narratives — the abortionist’s instruments, the impersonal clinic — that have historically served as persuasive scare tactics.

• .. What the anti-abortion movement has thought through carefully is how to tell stories about abortion’s impact. Early activists, who were mostly Catholics, were almost solely concerned with saving the life of the fetus.
• Feminists arguing for choice, in turn, made a convincing case for their own rights — and accused people opposed to abortion of not caring about women at all.

.. By the 1990s, emphasizing abortion’s supposed harms to women had become a full-fledged strategy, one that changed both the public face of the anti-abortion movement and its self-identity. Today many young anti-abortion activists frame their work as feminist

.. Promoting abortions as murder had always carried the uncomfortable implication that the women who procured them were killers. In the revised narrative, ‘‘the women are viewed as essentially victims,’’ Williams says. ‘‘The argument is always that they didn’t have the knowledge they really needed.’’

.. And ‘‘abortion pill reversal’’ implies exactly that — that a woman made an uninformed decision and has now thought better of it. The brainchild of a San Diego doctor named George Delgado, ‘‘reversal’’ is a medical protocol that floods a woman’s body with progesterone, the so-called pregnancy hormone, within hours after she has taken mifepristone, the drug that begins a medication abortion. ‘‘If you have something that’s poisoned a specific spot in your body and we know what the antidote is, then you just take the antidote,’’

.. For all the challenges that the abortion pill poses to the anti-abortion movement, it turns out to have at least one unexpected benefit: The hours between the two doses of medication represent an extra decision point to interrupt and redeem. ‘‘With a surgical abortion, once the instrument enters the uterus, then it’s over,’’ Delgado says. Medication abortion, by contrast, gives women ‘‘a second chance at choice.’’

.. Natural Procreative Technology, a Catholic-friendly approach to women’s reproductive health. Developed by an anti-abortion OB-GYN named Thomas Hilgers who was also inspired by ‘‘Humanae Vitae,’’ ‘‘NaProTechnology’’ eschews most forms of birth control and fertility treatments and relies instead on tracking widely used ‘‘biomarkers’’ like cervical mucus and body temperature.

..  he knew that mifepristone, the first drug in the abortion-pill protocol, works by blocking progesterone from the uterus. Couldn’t an extra dose of progesterone overcome the mifepristone? Within hours, he sketched out a plan to inject the woman with 200 milligrams of progesterone and to con­tinue giving the progesterone until the end of the first trimester.

.. Delgado later found out that a doctor in North Carolina, Matthew Harrison, had received a similar call from a crisis pregnancy center in 2006 and independently made the same guess about progesterone counteracting the effects of the mifepristone. That fetus, too, survived, after the mother received progesterone injections through her 26th week of pregnancy.

.. They soon published a small case series in the journal Annals of Pharmacotherapy. The article, just four pages long, describes seven pregnancies treated with progesterone after mifepristone. Two of the abortions completed, but four of the fetuses survived.

.. Delgado’s hotline received just 28 calls in all of 2012. But the volume increased over the years: 200 calls in 2013, more than 400 in 2014 and more than 600 for each of the last two years

.. When a call comes into the hotline, the nurse’s job is to connect the caller as quickly as possible with a local doctor willing to administer the reversal protocol. The program has a network of about 350 doctors

.. If the caller doesn’t live within driving range of one of those providers, the hotline nurse immediately starts calling local doctors and hospitals to explain what reversal is, hoping to find a sympathetic provider. Catholic hospitals are usually a good place to start.

.. One fan gave Harrison a T-shirt that read ‘‘Reversed RU-486. Now reverse Roe vs Wade.’’

.. A vanishingly small percentage of women decide they want to reverse a medication abortion halfway through. In fact, regret is quite rare when it comes to abortions in general. A 2013 study found that although women experienced a wide range of often conflicting responses to the procedure, relief was the most common emotion one week after. A later study found that women who had abortions were also confident in their decisions beforehand — more confident than people who decide to get reconstructive knee surgery, for example.

.. ‘Most women are certain of their decision when they present for care,’’ says the study’s lead author, Lauren Ralph, an epidemiologist at the Univer­sity of California, San Francisco. Their certainty is largely unchanged by waiting periods and mandated counseling, which suggests ‘‘women do not change their minds.’’

.. Ralph also found that women who do experience uncer­tainty are more likely to already believe a myth about abortion, such as that it causes breast cancer.

.. In Cynthia’s memory, it wasn’t the pressure from a priest, a doctor, her mother and her boyfriend that changed her mind. It was the ultrasound. ‘‘When I saw the heartbeat, I mean, truly everything changed,

.. Women who regret their abortions, and are willing to speak publicly about it, have long been valued spokeswomen for the anti-abortion message. But reversal offers a twist to those stories: a happy ending.

It also represents a concrete action that women can take to atone for their initial mistake.

.. While Delgado claims that flooding a woman’s body with progesterone saves the fetus, other doctors say that in many cases the fetus would have survived if the woman simply declined to take the second pill, misoprostol, after the initial dose of mifepristone.

.. The American Congress of Obstetricians and Gynecologists issued a strongly worded statement against reversal in 2015 that said the fetus would survive 30 to 50 percent of the time.

.. The question, in other words, is whether the progesterone protocol is effectively just a placebo. ‘‘There’s no evidence that any kind of treatment is better than doing nothing,’’

.. Delgado and Davenport are also preparing a larger case series for publication later this year, which they say will include about 350 women. Delgado says it shows that the most effective progesterone protocol results in an embryo survival rate between 60 and 70 percent.

.. Critics say that even if those numbers are valid, they aren’t what they seem. Many women who decide to take progesterone undergo an ultrasound first, to see if the pregnancy remains viable; those whose fetuses have died do not go forward with reversal, which means the initial pool of subjects is skewed toward women whose pregnancies had a good chance of continuing even without progesterone.

.. The protocol, however, has attracted almost no interest from the mainstream medical community, in part because the presumed audience is so small.

.. Since 2015, legislators in 10 states have introduced bills requiring doctors to inform women procuring the abortion pill that they can change their minds after taking the first dose. ‘‘These laws are essentially forcing physicians to tell their patients about a treatment that is unproven and essentially kind of encouraging them to participate in an unmonitored research experiment,’’

.. The anti-abortion movement has effectively promoted the idea that many women regret their abortions. Supreme Court Justice Anthony M. Kennedy, considered a wild card on abortion questions, waxed eloquent on the topic in his ruling in Gonzales v. Carhart, a 2007 case that upheld the ban on ‘‘partial-birth’’ abortion. ‘‘It seems unexceptionable to conclude some women come to regret their choice to abort the infant life they once created and sustained,’’ he wrote in the majority opinion. ‘‘The state has an interest in ensuring so grave a choice is well informed.’’ That assumption undergirds huge swaths of contemporary abortion law: waiting periods, mandatory ultrasounds and requirements that doctors give women more (sometimes dubious) information about the procedure and its effects. The idea seems to be that many women understand what an abortion is only after they have one.

.. Stories from individual women who struggle with remorse remain a powerful weapon in the anti-abortion arsenal, and the abortion rights movement has often stumbled in its attempts to respond.

.. Just raising the question of uncertainty and regret affects the abortion pill’s reputation. ‘‘You’re changing cultural norms about what people think about this kind of abortion,’’ she says. ‘‘You can do that regardless of what the research ultimately shows.’’