In a Republican presidential field full of candidates opposed to abortion rights, Mike Pence stands out in his embrace of the cause.

The former vice president, who is seeking the White House in 2024, is the only major candidate who supports a federal ban on abortion at six weeks, before many women know they’re pregnant. He has advocated pulling from the market a widely used abortion pill that has a better safety record than penicillin and Viagra. And he’s implored his Republican rivals to back a 15-week federal ban as a minimum national standard, which several have not done.

In a recent interview, Pence went even further, saying abortion should be banned when a pregnancy isn’t viable. Such a standard would force women to carry pregnancies to term even when doctors have determined there is no chance a baby will survive outside the womb.

“I’m pro-life. I don’t apologize for it,” Pence said in the interview. “I just have heard so many stories over the years of courageous women and families who were told that their unborn child would not go to term or would not survive. And then they had a healthy pregnancy and a healthy delivery.”

Doctors disputed Pence’s characterization, saying there are conditions that are always incompatible with life and others where the chance of survival is so slim that most patients, when previously given the choice, concluded that continuing the pregnancy wasn’t worth the suffering, grief or risk.

Pence, however, says he’s undeterred.

“I want to always err on the side of life,” he said. “I would hold that view in these matters because … I honestly believe that we got this extraordinary opportunity in the country today to restore the sanctity of life to the center of American law.”

Those comments place Pence firmly to the right of the rest of the 2024 presidential field and alone among GOP candidates, who largely declined to take a stance on the issue. And they drew alarms from obstetricians and doctors who specialize in high-risk pregnancies and say nonviable pregnancies are far more common than people realize. They range from ectopic pregnancies, when an embryo implants somewhere other than the uterus, to deadly birth defects and other severe pregnancy complications.

Banning abortions in these cases, doctors say, leads to outcomes that are both cruel and put women’s lives and mental health at risk.

“One of the things that you cannot understate is the difficulty for a woman to carry a nonviable pregnancy,” said Alan Peaceman, professor emeritus of obstetrics and gynecology at Northwestern University’s Feinberg School of Medicine. “It is psychological torture to go out in the world, for people to see your pregnancy — and people will come up to you and want to talk about your pregnancy. And that puts the woman in a terrible position that nobody should be in unless they chose to be in that position.”

Once an issue largely hidden from public view, nonviable pregnancies have gained attention since the Supreme Court ended the constitutional right to an abortion last year, ushering in a wave of bans and restrictions in Republican-led states. Those moves have implications not only for unwanted pregnancies but also for cases where women receive heartbreaking diagnoses, often when they’re months along into pregnancies that were deeply desired.

In states like Texas, Florida and Louisiana, women have described the anguish of being denied abortions even when they know their babies will be stillborn or die shortly after birth. Some have had to wait until they developed life-threatening infections for intervention. Others have spent thousands of dollars to travel to states where the procedure is still allowed.

Sarah Prager, a professor of obstetrics and gynecology at the University of Washington Medical Center, said she and her colleagues have seen a steady stream of patients coming from states where abortions are now banned. About 11% of those patients, she said, have received a serious diagnosis, including cases where there is no chance of the fetus surviving.

“They are often absolutely shocked to learn that the abortion laws also prohibit them from being able to get care to be safe,” she said, “even though they knew these laws were in place in this state.”

Spokespeople for former President Donald Trump and Florida Gov. Ron DeSantis declined to say whether they back Pence’s position. Trump, the early front-runner, has repeatedly said he backs exceptions in cases of rape, incest and the life of the mother and has blamed hard-line abortion stances for costing the party in last year’s midterm elections.

DeSantis, who is polling a distant second, signed a six-week ban in Florida that includes an exception for fatal fetal abnormalities, along with rape, incest and to save the mother’s life. He has declined to say whether he supports a federal ban.

South Carolina Sen. Tim Scott’s campaign pointed to an article that did not address the question of unviable pregnancies. A spokesman for former U.N. Ambassador Nikki Haley said only that she “will sign pro-life legislation that includes exceptions for rape, incest, and for the life of the mother,” suggesting she, too, may be opposed to an exception for nonviable pregnancies — but declined to clarify.

Pence’s push to end abortion puts him at odds with the majority of Americans who are broadly opposed to the Supreme Court’s Roe v. Wade reversal.

While most favor at least some restrictions, a majority of U.S. adults say abortion should be legal during the first weeks of pregnancy, even in states with the strictest limits, according to a new poll from The Associated Press-NORC Center for Public Affairs Research.

But Pence, an evangelical Christian, for whom the issue is deeply personal, argues restricting abortion is “more important than politics” and calls it the “cause of our time.”

As he works to appeal to conservatives in states like Iowa, Pence also points to the issue as one that distinguishes him from his GOP rivals, contrasting himself with “some people in this field now who want to relegate this issue to just a debate among the states.”

Pence does say he has “always supported” exceptions for rape, incest and to save the life of the mother, though he told an Indiana anti-abortion group in 2010 that he believed, “Abortion should never be legal,” and later that it should only be legal to save the “life of the mother.”

There are a number of fetal conditions in which doctors generally agree there is “truly zero probability for a healthy outcome,” including anencephaly, a severe neural tube defect in which the skull doesn’t form and the brain is exposed, said David Hackney, a spokesperson for the Society for Maternal-Fetal Medicine and a high-risk obstetrician in the Cleveland area.

“The chances of survival are absolute zero … no matter what Mike Pence says,” he said. In such cases, he said, “it feels absurd” for people to be “forced against their will to carry pregnancies to term.”

But other cases are grayer. Take premature rupture of membranes, when the water breaks early, often in the second trimester, leaving a fetus without the amniotic fluid that protects it and supports the development of organs, including the lungs. In those cases, survival generally depends how early the rupture has occurred.

Hackney said with early membrane rupture, “you do have rare survivors,” but that “exceedingly poor prognosis” comes with a litany of risks, including hemorrhaging, blood loss and dangerous infection, which can cause permanent infertility, shock and sepsis as women wait to deliver or qualify for abortions under “life of the mother” exceptions.

That’s what happened to Savita Halappanavar, the 31-year-old woman who died in Ireland in 2012 of sepsis after she was denied an abortion, prompting the country to overturn its longstanding ban.

Rachel Neal is a fellow with Physicians for Reproductive Health and an OB-GYN in Georgia, where abortion is outlawed after cardiac activity is detected, around six weeks. While the state provides an exception in cases in which the “physician determines, in reasonable medical judgment, that the pregnancy is medically futile,” she said water breaking in the late second trimester would typically not be covered.

That means women who previously had the choice to end their pregnancies early now either have to leave the the state or wait to deliver a baby that will likely die immediately or shortly after birth, while putting themselves at high risk of infection that could impact their ability to get pregnant again.

“It’s completely uncharted territory,” Neal said. “Before all of this, almost nobody chose this. … It was very uncommon that someone would choose to wait … because realistically any outcome that would result in a live birth is so slim.”

Nine states with abortion restrictions explicitly exempt cases of lethal fetal anomalies, according to the Guttmacher Institute, a research group that supports abortion rights. Even in states with such exemptions, however, doctors say there can be confusion.

Some states have developed lists for what qualifies as a fatal fetal condition, but doctors say they will never fully capture every potential diagnosis. And most states do not have such lists, leaving definitions up for interpretation.

“How lethal does it have to be?” Peaceman asked. “Does it have to die within the first few hours? Or the first 30 days?”

At the same time, doctors in some states risk felony convictions that can carry five or 10 years of mandatory prison time if others dispute their interpretations of what some complain are overly broad and confusing rules.

Eric Scheidler, the executive director of the Pro-Life Action League, a nonprofit that advocates against abortion, accused “politically motivated physicians” of focusing on “edge cases” to “maintain a broad abortion license” and in some cases “deliberately misunderstanding what the law says in order to create this narrative that we have to have complete abortion license or we’ll have physicians caught in a quandary.”

Nonetheless, he said he thinks candidates should focus on the majority of abortions and not these kinds of cases.

“I really want to see these candidates talk about where we have areas of broad consensus,” he said. “I would encourage political candidates to espouse positions that are widely held. … I don’t want to get hung up on these very rare cases.”