When Mana Parast examines a placenta, she knows she may never find the answers she seeks. She’s hunting for clues — strips of dead tissue that signal autoimmune disease, white blood cells in the lining of the umbilical cord that point to an infection, thickening that could suggest blood wasn’t flowing freely to the fetus.

She wants to be able to tell a parent what she thinks went wrong.

Parast is one of just a few physician-scientists in the U.S. specializing in perinatal pathology, an overlooked and underfunded field tasked with analyzing fetal tissue, placentas, and other so-called products of conception to sleuth out why a mother miscarried — and hopefully, prevent further losses.

After a miscarriage or stillbirth, placentas — the temporary organ that protects and nourishes a fetus for the duration of a pregnancy — can harbor important evidence. While the majority of pregnancy loss is the result of genetic abnormalities, tightly wound umbilical cords, placentas that suddenly stop growing, and evidence of scarring are also clues in the 100 to 120 cases Parast and her team investigate each year. But for all of perinatal pathology’s promise, every case, even the ones considered “solved,” reveals just how little modern medicine knows about pregnancy loss, and how much there is still to learn.

“I don’t think we should underestimate the utility of placenta pathology,” Parast, who serves as director of the perinatal pathology service at University of California, San Diego, said. “Having said that, it’s not a crystal ball.” It’s rare to identify a single cause for a fetal death, especially after the first trimester. And while there are a few causal explanations for pregnancy loss — conditions in which no fetus could ever survive — most are merely correlational.

Hospital pathologists like Parast are also trying to offer comfort. In the U.S., as many as 1 in 4 pregnancies end in miscarriage or stillbirth. Those who experience pregnancy loss often feel personally responsible. “When an answer or explanation for their loss was given, [parents] were less likely to blame themselves,” said Jonah Bardos, an OB-GYN at the University of Miami and the co-author of a 2015 national survey on public misconceptions of miscarriage.

But pathologists with perinatal expertise are increasingly worried about the pressure they face to produce definitive cause of death determinations from law enforcement officials. Police and prosecuting attorneys have always had an interest in investigating pregnancy loss — acting on the suspicion that some miscarriages and stillbirths are intentionally caused by, or otherwise the fault of, the mother. Between 1973 and 2020, there have been more than 1,700 cases of arrests, detentions, and “equivalent deprivations of personal liberty” of pregnant people, according to the nonprofit Pregnancy Justice. In a post-Roe era, legal experts worry similar cases may gain more traction going forward.

Pathologists hope to be prepared. Less than two weeks after the Dobbs decision was finalized, the College of American Pathologists called for a special committee to meet to discuss its implications for the field. “We wanted them to think about it from the point of, where could a pathologist get tripped up — could get in trouble — doing what they’ve always done?” said Emily Volk, a physician and president of the college.

Over the next four months, group members, including Parast, met regularly to develop new guidelines. They aim to address pressing concerns, including when a pathologist can identify evidence of an abortion (and when they cannot) and how to properly dispose of tissues. Volk expects the results to be published sometime this spring, though they will need regular refinement to keep pace with state legislation.

“We’re very much in the middle of all of that right now,” Parast said.

Michael Caplan, a forensic pathologist with more than 30 years of experience in autopsy labs in five states, knows the day will come when he’ll need the kind of guidance those groups could provide. For example, if he examines a fetus and finds no fetal or placental abnormality, will the absence of evidence be used as evidence for self-managed abortion?

“I can see it coming down,” Caplan said. “There is going to be … pressure to report these things.” He added: “We need to decide as a group how we’re going to handle these situations.”

“We need to decide as a group how we’re going to handle these situations.”

Michael Caplan, forensic pathologist

In May 2015, Susan Valoff had packed her bag for the hospital, dropped her son Peter off at day care, and put in a half day at work. That afternoon, she was scheduled to deliver her second child, a boy to be named James Owen, via C-section. But when Valoff arrived at her obstetrician’s San Diego office for her final appointment, the exam that just one week ago had revealed a steady fetal heartbeat was now eerily silent. An ultrasound confirmed James had died.

After James was delivered, Valoff and her husband, Scott, held their baby. A photographer, provided by the hospital, took the only pictures they would ever have of their son. The couple decided against an autopsy, but they did agree to share the placenta for examination by a pathologist contracted by the hospital. Six days later, Valoff received the results.

The pathologist identified inflammation in the placenta — perhaps resulting from some infection of the amniotic fluid. He hinted that this may have caused the loss. But Valoff said these findings left her with more questions than answers. Her pregnancy had been “high-risk”: She was 45 years old, conceived James using IVF, and had undergone a C-section before — all of which increased her risk of miscarriage or stillbirth. Surely that had something to do with James’ death.

Online, Valoff found a pathologist who specialized in stillbirth and infection. He had recently retired, but recommended she reach out to Parast, who worked just down the road. Parast agreed to provide a second opinion. Inflammatory cells indeed indicated infection, she concluded. But she didn’t think that was to blame. Instead, Parast suggested that James died as a result of villitis, an inflammatory condition that restricts fetal growth.

While a detailed perinatal pathology is not exactly comforting, it can offer some of the clarity that parents like Valoff crave. “That’s the story you tell yourself and everyone you know the whole rest of your life,” Valoff, now 53, said. “That story matters.”

Valoff later discovered that the first report came from a pathologist who didn’t specialize in placentas. That kind of expertise is rare: There are just 700 members of the Society for Pediatric Pathology globally, and pathologists with expertise in the placenta — what Parast calls “the diary of intrauterine life” — make up just a fraction of their ranks.

They take their work seriously. “Our only job is to provide as much information [to the patient] as possible to make the best decision possible for her and her subsequent pregnancies,” Parast said. Or at least that’s what she believed — until she heard about an incident at the U.S.-Mexico border wall.

The placenta on the examination table was like any other. But it came from a migrant woman who was 35 weeks pregnant when she fell at the border wall, Parast recalled. Her baby was stillborn. The medical examiner in San Diego was now investigating whether or not she had intentionally harmed the fetus.

Parast agreed to take a look. There was clear evidence of a placental abruption, which happens when the placenta separates from the uterine wall before birth, Parast remembers writing in her report. But Parast knew that did not indicate anything about intent. She doesn’t recall ever hearing back about the outcome of the case.

Parast had interacted with law enforcement before. In a residency rotation at the Atlanta medical examiner’s office, Parast often reviewed difficult cases, including those involving children. But she said she failed to appreciate the entwinement of medicine and the law until authorities asked her to look into the migrant woman’s miscarriage.

“That was my first aha moment of, what are you asking me?” Parast said.

In hindsight, it’s clear that reproductive medical researchers have been walking a vanishingly thin line. For decades, they have worked to unravel the mysteries of pregnancy loss to help patients who want to have children get pregnant and carry safely to term. But they’ve also been building a body of knowledge that, in the wrong hands, may be used against women who lose their pregnancies.

To many families, the work of perinatal pathologists is invaluable. Doctors now know that diagnosing and treating autoimmune conditions like lupus can help people carry a child to term. They also have a far better understanding of how to screen for the embryos with the best chance of a healthy pregnancy during the IVF process. And patients, too, are armed with the knowledge they need to monitor their own pregnancies, such as by keeping fetal movement journals that could help them recognize an issue in time to swiftly act.

“It’s the pathologist that provides the basis for all the clinical care that comes after,” Volk said.

But many losses still can’t be prevented, and some fetal deaths can not be explained. A person could do everything “wrong,” and still have a perfectly healthy live birth. And person could do everything “right,” and lose their pregnancy anyway. “The public sentiment is a little skewed by how much we’ve gotten the message that we can control things,” said Lara Freidenfelds, a science historian and author of “The Myth of the Perfect Pregnancy: A History of Miscarriage in America.”

In a courtroom, that narrative of control can have devastating consequences. Autopsy reports and related findings can form the basis of homicide, “feticide,” child abuse, and assault charges. To date, U.S. women have been investigated for everything from attempting suicide to falling down the stairs while pregnant.

Even the esoteric language of pathology may itself pose a risk. Take a term like “molar pregnancy,” which describes a tumor that develops in the uterus. Doctors know that if an embryo is present, it isn’t viable, but others might not. “That may not be clear to the patient from whom that specimen came,” Volk said, “but it also may not be clear to a district attorney or a lay policymaker or a lay state representative.”

In 2006, a 16-year-old named Rennie Gibbs delivered a stillborn daughter, who she named Samiya, at a hospital in Mississippi. Gibbs was later charged with “depraved heart murder” — which could carry a lifetime prison sentence — after a medical examiner ruled the cause of death was “cocaine toxicity.” Gibbs had used illicit substances while pregnant. But expert witnesses challenged the notion that cocaine could be said to cause a stillbirth, as it hasn’t been proven to end pregnancies. These same biomedical researchers also identified the more likely cause of Gibbs’ stillbirth: the umbilical cord wrapped around Samiya’s neck — a factor no one could control. In 2014, after years of legal proceedings, a judge finally dismissed Gibbs’ case.

These cases can happen anywhere, even in ostensibly blue states. In California, two cases of women prosecuted for using drugs while pregnant, and later losing their pregnancies, have recently captured public attention. “Prosecutors don’t have to be anti-abortion ideologues to prosecute people,” said Farah Diaz-Tello, senior counsel and legal director for If/When/How, a reproductive justice organization. Rather, “it’s an allegiance to their interpretation of law and order.”

The gap between the scientific doubt inherent to medicine and the legal certainty a court desires can leave pathologists in a bind. “There is no such thing as absolute determination,” Parast said. “If anyone said so, they’re lying.”

Caplan, the forensic pathologist, has walked this line before. He has dedicated his life to giving a voice to the dead, but he said decades of experience have only taught him how little he knows.

As a forensic pathologist working in the medical examiner’s office in the 1990s, Caplan struggled to reach definitive conclusions in cases of children who died of SIDS. So he went back to school to train in pediatric pathology. There, and in the years since, he’s learned about differences in anatomy, physiology, and responses to injury across the lifespan that help him do his job — and the shortcomings of forensic methods like the widely disproven 17th-century “float test” that some U.S. officials still use to determine if a baby was born alive.

To Caplan, being able to confront the horizon of scientific knowledge can be empowering in a difficult and delicate line of work.

“I know that my limitations aren’t from my lack of effort,” he said.

Yet Caplan worries about what might happen if other pathologists fail to stick to the scope of their expertise. “I can’t change my objective findings,” Caplan said. But, he added, pathologists should “never, ever overextend the interpretation” of those findings.

As individuals, forensic and hospital pathologists are limited in the steps they can take to advance reproductive justice, while still doing their jobs. They can push back on the use of flawed methods like the floatation test, or provide expert opinions in court that cast scientific doubt on a prosecutor’s claims.

They can even take care not to speculate about things like self-managed abortion in their autopsy reports. “I would never use that language, ever, on a fetal death certificate,” Caplan said. Without definitive evidence, he would opt for a phrase like “fetal death of undetermined cause.” While subjective musings could be incorporated in a “comment” or “opinion” section, Caplan argues “it is better to allow opinions to be expressed and expanded in legal proceedings such as depositions and trials.”

But pathologists will need support, including as they continue their research. “I think there’s a concern that fear of committing a felony will make researchers or physicians more reluctant to engage in this kind of research,” said Robert Silver, an OB-GYN at the University of Utah who specializes in pregnancy loss, “and it will also make families more reluctant to engage in this kind of research.”

Guidelines from professional organizations like the College of American Pathologists will help, as would solidarity with other medical and non-medical specialties, including reproductive justice advocates, politicians, and lawyers. For example, in September, California abolished a law that had previously required coroner’s investigations into all stillbirths. Even in states where abortion is now illegal, similar legislation could, at a minimum, shield some pregnant people from criminal charges.

Back in Parast’s lab in La Jolla, the pathologist feels a mix of fear and fierce determination to keep providing her patients answers. “As a researcher, you don’t set out and think, I want to do research at the edge of what’s controversial — especially in this area that’s so underfunded,” she said. “You’re in this area because you have a passion for women’s health.”