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The Republican debate over abortion has centered around one number: 15. Backers of a 15-week federal ban tout it as a compromise measure, even in the face of recent electoral defeat.

Anti-abortion advocates hope congressional candidates will embrace this measure, and they’re pushing GOP presidential candidates to promise they would sign such a bill.

Front-runner and former President Donald Trump has not endorsed a 15-week abortion ban but has not rejected one — saying instead that he would “come together with all groups” to find a mutually agreeable state or federal policy. It’s unclear what that would be.

Other candidates in the running have weighed in as well: Florida Gov. Ron DeSantis said he would sign a 15-week ban, and former South Carolina Gov. Nikki Haley has publicly called such a ban “unrealistic,” noting the challenges in getting such a proposal through Congress. SBA Pro-Life America, a major anti-abortion lobbying group, told news outlets including The 19th that Haley has privately committed to signing such a proposal if elected. Her campaign has denied this. 

Fifteen-week measures represent a massive shift in how Republicans have discussed abortion bans. Proponents have said a 15-week cutoff would outlaw the procedure at a point when fetuses can feel pain. But as recently as two years ago, language about “fetal pain” and “late-term abortions” was used to justify not 15-week bans, but 22-week ones. 

The science has not changed, medical researchers, physicians and legal experts said. Mainstream scholarship suggests that all the elements necessary for a fetus to experience pain — including not only pain sensors but also the brain components to translate that sensation into actual feeling, including the cerebrum — do not develop until far later in pregnancy, at least 24 weeks and possibly closer to 28 weeks.

“The cerebrum is key, and those connections to the cerebrum don’t occur until after 24 weeks,” said Dr. Steven Ralston, a maternal-fetal medicine specialist at George Washington University and one of the authors of the Society of Maternal-Fetal Medicine’s clinical guidance to fetal pain. “Pain isn’t possible.”

Dr. Melissa Simon, a professor and practicing OB-GYN at Northwestern University, added: “Fifteen weeks is an arbitrary number.”

Instead, the effort to rebrand when and how “fetal pain” might be experienced illustrates not a new medical consensus but a new political reality unleashed by overturning Roe v. Wade. 

Roe held that the U.S. Constitution protected the right to an abortion up until fetal viability. Now that it’s gone, abortion opponents and Republicans courting their support are walking a difficult line: looking for a ban as early as possible that they can promote, while avoiding the voter backlash harsher restrictions have elicited. Ballot measures that would eliminate state-based abortion protections have uniformly failed since summer of 2022. And pollsters and election strategists credit voters’ opposition to Roe’s overturn, and to Republicans’ embrace of abortion bans, with the party’s losses in the 2022 midterms.

The rhetorical link between 15 weeks and “fetal pain” is relatively new. Mississippi’s 15-week abortion ban — passed in 2018, and the law at the center of Dobbs v. Jackson Women’s Health Organization, the case that overturned Roe — never mentioned fetal pain. Documents that Mississippi filed to the Supreme Court in June 2020 requesting the high court weigh in on the law made one of the first pain-based appeals for a 15-week abortion ban, arguing that “an unborn child can suffer pain by 15 weeks’ gestation.” 

In early 2021, national anti-abortion organizations continued to make pain-based arguments in their pursuit of 22-week abortion cutoffs — not 15. That year, major anti-abortion groups such as SBA Pro-Life America campaigned in favor of 20-week abortion bans, arguing that this was when fetuses could feel pain. In February 2021, National Right to Life, the organization credited with developing 22-week abortion bans in the early 2010s, characterized such legislation as the “Pain-Capable Unborn Child Protection Act.”

The groups also were pushing bans earlier in pregnancy, and most anti-abortion lawmakers focusing instead on earlier six-week abortion bans, meant to cut off abortion access at the first sign of fetal cardiac activity. (Such laws are often described as “heartbeat bans,” even though a fetal heart doesn’t exist at that point in pregnancy.) 

It wasn’t until 2022, after the court agreed to hear the Dobbs case, that abortion opponents began to link 15-week bans more regularly to fetal pain: DeSantis used the argument when signing the state’s 15-week abortion ban in April 2022. Months after Roe’s overturn, Republican Sen. Lindsey Graham introduced a proposal for a national 15-week ban — a proposal most Republican lawmakers quickly distanced themselves from — he described the bill, endorsed by SBA Pro-Life America, as a protection for “pain-capable unborn children.” Graham had used identical language in 2013, 2015 and 2017 when introducing proposals for a 22-week abortion ban. 

Although there is no medical or scientific argument for a 15-week ban, abortion researchers and pollsters said, there may be a political one.

Most Americans oppose abortion bans, but their criticism is sharpest for those that cut off access early in pregnancy. If there is a tipping point, public opinion research suggests it could fall around 15 weeks, said Mallory Newall, a vice president at Ipsos Public Affairs, which has polled extensively on the issue. That appears to be the earliest point in pregnancy where a majority of Republicans are in favor of a ban — though it’s still not clear that voters in general will feel the same way. Ipsos polling conducted this past April found that 56 percent of Republicans either strongly or somewhat supported a 15-week ban, compared with 49 percent of Independents and 30 percent of Democrats. A six-week cutoff polled far worse, with majorities across all affiliations disapproving.

“It’s trial and error, especially at the federal level,” said Patrick Brown, a fellow at the Ethics and Public Policy Center, a conservative think tank. Many polls showing broad support for an abortion cutoff at 15 weeks were conducted before Roe’s overturn, he noted, when such a ban was still only theoretical.

“It’s just a matter of people trying to put their finger in the wind and feel where the wind is going,” Brown said. “People like round numbers and easy heuristics. It would be weird to come out with a ban after, say, 11.5 weeks.”

In a statement to The 19th, SBA Pro-Life America cited fetal pain, but also emphasized political considerations in its support of a 15-week ban. 

“It will take time to build a culture of life in the United States,” said Mary Owens, a spokesperson for the organization. She described a 15-week ban as “the current national American consensus” policy — citing polls indicating voter support — while also arguing that such a policy would protect fetuses “when they can feel the pain of the abortion.”

Proponents of a 15-week ban point to a narrow set of studies to justify their arguments, arguing that they support the notion of fetal pain existing that early in pregnancy. But mainstream researchers have widely criticized their use and interpretation of the medical literature. And the same arguments being made for a 15-week ban could be applied to earlier and earlier cutoffs, such as an eight-week ban, Ralston said. 

“They may be saying 15 weeks now, but it’s not clear to me they will stay there,” he said.