Despite having lived much of her adult life alongside tabloid photographers, Catherine, the Princess of Wales, is not generally prone to oversharing. Unlike her American sister-in-law, Meghan Markle, the Duchess of Sussex, Catherine tends to prefer to stick to the script. Her vibe is low drama, with a perfect blowout. Two years ago, after she cancelled several appearances following a cancer diagnosis, she waited so long to publicly announce her illness that the internet exploded with conspiracy theories. (She was not, after all, in recovery from a bad haircut or a Brazilian butt-lift.) However, in 2012, when she became pregnant with her first child, George—now second in line to the throne—she was forced to reveal this condition early. She couldn’t wait the customary twelve weeks before sharing the news because she was in the hospital, being treated for severe dehydration. Even princesses puke their guts out.

Most people have heard of morning sickness. But when Catherine, then known mostly as Kate Middleton, became ill, it was the first time that many learned the term hyperemesis gravidarum, or H.G., which translates quite literally to “excessive vomiting during pregnancy.” The clinical definition of H.G. varies, but it refers to a disease characterized by extreme nausea and vomiting that goes beyond what is expected when you’re expecting. It is debilitating, and can be life-threatening for both the mother and the fetus; untreated, the fetal-loss rate is up to thirty-four per cent. No sign of these horrors appeared on Catherine’s person as she was discharged from the hospital. She left coiffed and smiling, holding yellow roses and mouthing the words “much better” to the assembled press. Yet her name is so linked to the condition that a friend of mine, in the depths of H.G., found solace in telling people she had “a touch of the Kate Middletons.”

Some women take a less discreet approach. Consider the Amy Schumer documentary “Expecting Amy,” from 2020, in which Schumer, besieged unexpectedly by H.G. in her first pregnancy, documents her struggle in unsparing detail. There’s footage of her throwing up at home, but also in various vehicles, while recording a podcast, and before the start of shows. Her health becomes so unwieldy that she incorporates it into her act, shooting a promo for her special “Growing,” in which she pretends to vomit using what looks like oatmeal as a prop. She’s filmed being hospitalized and receiving intravenous fluids. Most of the time, she is able to joke about her condition, but sometimes she cracks. “I resent the culture and how much women have to suck it the fuck up,” she says at one point. “Do I sound like a little whiny bitch?”

In the early-two-thousands rom-coms of my youth, a demure puke was often the first, sometimes the only, sign that our stylish heroine’s life was about to change, big time. The ambitious television reporter played by Katherine Heigl in “Knocked Up,” gets her first inkling that she might be pregnant when she throws up during an on-camera interview with James Franco. In “Juno,” the twee 2007 film about teen pregnancy, Elliot Page’s character, attempting to conceal her condition, pukes the remnants of a blue slushie into her stepmother’s vase. “I would never barf in your urn, Brenda,” she says at dinner, when confronted. Like fainting, craving pickles, or struggling to wiggle into skinny jeans, vomiting, in the cultural imagination, is a stand-in for imminent motherhood, as legible as any pregnancy test.

Some amount of morning sickness—a misnomer, since it can strike at any hour—is a normal part of many pregnancies. A woman’s sense of smell can increase; you may be able to sniff out the raw meat at a butcher shop, your neighbor’s shampoo as she walks by, or the contents of your dishwasher, with nauseating effects. Your morning cup of coffee may become gag-worthy. But in H.G. even these symptoms are taken to an extreme.

Women with H.G. often become aware that they are pregnant from the sheer force of their nausea. In interviews with more than a dozen women who had experienced the disease, I heard stories of debilitating symptoms that started in the early weeks of pregnancy and often continued right up until birth. That’s nearly nine months of the worst hangover of your life. Some women vomited upward of twenty times a day; many had been hospitalized. There is no reliable pre-pregnancy test to determine if a woman will develop H.G., so first-time parents are often taken by surprise. One woman told me having H.G. felt like being “on a shipping boat in the Atlantic, in the middle of a storm, and you can’t get off, and the only relief is sleep or death. I’d vomit, and then briefly, there’d be half a second’s respite, and then [the nausea] was there again.” Another woman, in the last weeks of her pregnancy, told me, “It’s like I got dropped into a marathon I didn’t want to run.”

Studies show that the disease occurs in up to three per cent of pregnancies, though the real incidence may be higher, according to the Hyperemesis Education and Research Foundation (HER). The official figures only account for the most severe cases of H.G., in which women are treated for dehydration and other complications in the hospital. They do not account for untreated H.G., or for the many women who terminate their pregnancy because of the severity of their symptoms before receiving a diagnosis. A 2021 meta-analysis showed that up to sixteen per cent of women took anti-vomiting drugs during pregnancy. “Hyperemesis (HG) is not really a rare disorder,” the foundation says on its website. Despite its prevalence and severity, researchers have struggled to get resources. Funding from the National Institutes of Health for maternal-health projects has decreased by roughly forty per cent during President Trump’s second term. On moms.gov, a new website by the Department of Health and Human Services for new and expecting mothers, H.G. does not appear on a list of health conditions that may affect pregnant women. (The list is curiously short, featuring just four complications, including gestational diabetes and “depression among women.”) Marlena Fejzo, a geneticist at the University of Southern California who has devoted her career to studying H.G. since experiencing it herself, told me, “It’s the second leading cause of hospitalization in pregnancy after preterm birth, and yet it’s often not considered a pregnancy condition. It’s not taken seriously. And women are aborting.”

In May, I met with Fejzo at an international conference for hyperemesis gravidarum, held at a quaint hotel at the base of a fjord near Bergen, Norway. Fejzo is in her late fifties, petite and brunette, with birdlike features and a polite intensity. In the H.G. world, she is something of a celebrity; in 2024, she was named a Time Woman of the Year. In recent years, the research on H.G. has made startling leaps. Not long ago, many clinicians, including Fejzo’s own doctor, still regarded the illness as a psychological rejection of motherhood, or a bid for attention. Fejzo’s work has upended those assumptions, uncovering a distinct biological cause for H.G., and opening up new pathways for prevention, treatment or a cure. Speaking with me, Fejzo grew emotional. “It’s been a long road,” she said. “What happened to me is definitely a motivator. If this didn’t happen to me, I’m sure I would have given up long ago.”

An odd thing about the world of maternal health is that, because the research is so badly funded, often the leading experts on a given disease have come to it through personal experience. At the hotel in Norway, attendees gathered for a meet and greet in the lobby. Over non-alcoholic spritzes, I spoke with nurses, midwives, researchers, and activists who had developed an interest in the condition after surviving H.G. The crowd skewed heavily female. One red-headed midwife from Utah told me that she had lost a job she loved during a bad stretch of illness. Sara Vanover, a stay-at-home mom with rhinestone-studded glasses, had flown in from Indiana. She was hospitalized for seven weeks in her second pregnancy, she said, and had lost a tooth from the acidic bouts of vomiting. She pointed to her jaw to show me where being sick had caused bone decay.

The history of hyperemesis can be hard to stomach. As far back as antiquity, physicians have observed the dangers of excessive vomiting in pregnancy. Hippocrates noted that pregnant women who ate too little faced an increased risk of miscarriage. In the fourth century, Oribasius, the Roman emperor Julian the Apostate’s personal physician, in a set of guidelines for prenatal care, recommended long walks, fragrant white wine, and, occasionally, mustard. The tenth-century Persian physician Rhazes suggested small, protein-rich meals of chicken or goat to encourage good humors, and quinces and pomegranates to restore appetite. In the nineteenth century, doctors began to differentiate between normal levels of pregnancy sickness and the uncontrollable vomiting of H.G. They wondered where the symptoms were coming from. Was it a pelvic lesion? A rigid cervix? A bacterial infection? They prescribed cold drinks, opium, enemas, and hydrogen cyanide. As a last resort, they aborted the pregnancy, though many women, already weakened by months of illness, did not survive the procedure. Charlotte Brontë, the author of “Jane Eyre,” who died, at thirty-eight, a few months into pregnancy, in 1855, experienced “sensations of perpetual nausea and ever-recurring faintness,” according to her biographer and friend Elizabeth Gaskell. Though her death certificate lists the cause of death as phthisis, or tuberculosis, contemporary scholars believe she died of complications from H.G.

In the twentieth century, doctors turned their attention to the mind. If they could not find a solution rooted in the body, perhaps the problem was psychological. The cultural anthropologist Margaret Mead suggested that women experiencing nausea were being influenced by friends who were “setting the stage for how terribly she is going to feel” during pregnancy. (Those pesky friends!) In 1952, the psychiatrist Sidney Rosen noted, “Nausea and vomiting have been considered an unconscious manifestation of oral rejection of the fetus, a repudiation of femininity, self-punishment, and punishment of the father.”

Doctors began using “isolation therapy,” removing women from friends and family, and denying them a sick bowl, with the goal of getting them to accept the pregnancy. Philippe Deruelle, a professor of obstetrics at Montpellier University, told me that, before he helped revise France’s national guidelines for H.G., “the protocol was to put women in a dark room. She was not allowed to see family, or husband,” he said. No phone calls, no television, no meals. The hypothesis was, “If you cannot vomit anymore, if you are punished, then you will stop the vomiting.” One woman, who was treated at a hospital in southern France, in 2021, told me that she was placed in isolation three separate times, for a week each time. She was told, variously, that she was rejecting her baby because she was not grieving the death of a friend, and because she hadn’t resolved a difficult relationship with her brothers. In her second pregnancy, a few years later, she was again isolated and denied visits from her partner and young daughter. Another woman, who was hospitalized in central France, in 2018, told me that she was placed in a dark room for eight days, and prevented from turning on the light or opening the shutters. Doctors told her that she was sick because she wasn’t ready for the pregnancy and that she was “vomiting out her baby.” “These are traumas that will stay with me forever,” she told me. In 2022, when Deruelle went to revise the guidelines for H.G. in France, he found that some doctors were still isolating women. Even today, “When the doctor cannot treat H.G., they say, ‘O.K., we will send you to the psychiatrist.’ ”

The lack of knowledge around the disease has left many women in the wilderness, trying to treat themselves. Speaking with former patients, I found a range of approaches. When symptoms first arrived, women were often advised to eat frequent, small meals, take supplemental B₆ vitamins, and try ginger. (“Fucking ginger,” my friend who had H.G. said.) On online forums for H.G., women desperate to stop the nausea compare notes on alternative therapies, including acupuncture, Reiki, hypnosis, and microdosing marijuana. Many women were prescribed antihistamines or Zofran, an anti-vomiting drug which can be taken orally or, in more extreme cases, through a device, worn like a fanny pack, that injects continually into one’s body. I spoke with one woman, a dental hygienist who lives outside of Atlanta, Georgia, who was still dealing with medical debt from her Zofran pump, even as she entertained her six-month-old.

Fejzo grew up in West Los Angeles, part of a tight-knit family with three siblings. Her mother was a German-language professor, and her father was a judge. Fejzo excelled academically, played the flute, and ran cross-country. She eventually got a Ph.D. in genetics, at Harvard. In 1996, while working on a postdoc at the University of California, San Francisco, she became pregnant with her first child. She felt sick almost immediately. She struggled to keep food down, and was unable to work for eight weeks. She lost fifteen pounds and went to the emergency room twice to receive I.V. fluids. She felt awful, but by the second trimester she had mostly recovered. She went back to work and eventually gave birth to a healthy baby boy.

Two years later, she became pregnant again, with a girl, but this time the sickness was much more intense. “I didn’t think it could be worse,” she said. She couldn’t eat, drink, or move without “violently vomiting.” “I just had to lie completely flat on my back. If I sat up, even, I would vomit. It was like being paralyzed.” She stared at the ceiling while her nurse administered different medications to try to control the nausea, but nothing worked. She recalled foaming at the mouth like “a poisoned animal.” Her parents, who had recently retired, took turns caring for her, while her husband looked after their two year old. She shrank to less than ninety pounds, becoming so weak that she needed a buzzer to communicate. “I was really starving,” she said. Eventually, she had a feeding tube placed. She was too ill to visit her doctor in person, but he never came to see her at home. When her family tried to communicate the severity of her symptoms, he accused Fejzo of exaggerating to win the attention of her husband and parents. At fifteen weeks, she started bleeding, and when she arrived at the hospital she learned that she had lost the baby. Afterward, her milk came in. “It was really sad,” she said softly.

When Fejzo returned to work—now at the University of California, Los Angeles—she told her boss that she wanted to work on H.G. “She started laughing in my face,” Fejzo recalled. At the time, H.G. research was not considered a viable career path. She accepted a role studying ovarian cancer instead, and spent her free time collecting data on hyperemesis. Alongside her work, she pursued another pregnancy, by surrogate, and had twin daughters.

One of Fejzo’s brothers was a statistician at U.C.L.A., and he helped her put together a broad questionnaire about H.G. She wanted to know what medications people with H.G. were taking, if it would come back in subsequent pregnancies, and if it ran in families. “There were just so many unanswered questions,” she said. People found the survey on her brother’s website, and later through the HER Foundation, and sent their answers back to Fejzo. She noticed that women who reported H.G. were likely to have a relative who had also experienced it. She began collecting saliva samples from respondents, with the goal of running a genetic study. For years, she stored the samples in a freezer at her lab at U.C.L.A, devoting her weekends to expanding the collection.

Fejzo had also been working on a different approach. In 2010, her brother had bought her a 23andMe DNA test for her birthday. Fejzo noticed how much data the company was collecting through supplemental surveys. She called a number there and asked if they could add a few questions on H.G., and they agreed. A few years later, they had collected enough data to run a genome-wide association study. In 2015, Fejzo applied to the N.I.H. for funding for a study that would use both the 23andMe data and the fifteen hundred saliva samples she had collected in her lab freezer. Her application was denied. “It wasn’t even reviewed,” she told me.

Fejzo applied for N.I.H. funding again in 2016, and was again denied. Finally, she secured grants from the Eppley Foundation, which funds innovative scientific research, and the HER Foundation. In 2018, Fejzo and her colleagues published a paper identifying a gene linked to H.G., which codes for a hormone called GDF15. In 2022, she published another study which confirmed the link between H.G. and the gene. A third study, published the following year in collaboration with an international team, showed how the hormone predisposed certain women to H.G. Two and half decades after experiencing H.G., she had found its cause.

The reaction from the medical community was ecstatic. Deruelle, the French obstetrician, described Fejzo’s work as “monumental” and a “definitive turning point in maternal medicine.” “For decades,” he wrote to me, “HG was profoundly misunderstood, frequently dismissed by the medical establishment as a psychosomatic response or a manifestation of psychological resistance to pregnancy.” Fejzo’s research had shown a biological cause. “Her work delivers an invaluable gift to millions of suffering women worldwide,” he went on. It allows clinicians to state “with absolute scientific certainty that ‘it is not in your head.’ ”

Fejzo had never heard of GDF15 before it showed up in her research. A naturally occurring hormone, it exists at some level in all humans—whatever sex, pregnant or not—and causes food aversions and vomiting when the body is under stress. (It has been observed in cancer patients who are unable to stomach food while undergoing chemotherapy.) It may have developed as a protective measure, a holdover from a time when leaving home to find food was risky. “We think it evolved as a way to tell you that you’re more likely to survive if you don’t go out searching for food,” Fejzo said. “If you were in a weakened state because some part of your body was ill, or under some kind of stress, and you went out searching for food, you’d be more likely to get attacked by a lion, or die from eating something poisonous, or catch some kind of infection.”

During pregnancy, the placenta produces high levels of GDF15, and the sudden increase triggers the queasiness we associate with first-trimester morning sickness. Once upon a time, this may have been helpful in warning pregnant women away from dangerous foods: lethal berries, raw meat. But women with H.G. experience a turbocharged version of this change. Most women who experience H.G. carry unusually low levels of GDF15 before pregnancy, often because of a variation in their genes, so that when they become pregnant the rise in the hormone is dramatic and destabilizing. One theory is that this can then prompt a stress response that releases more of the hormone, sending the woman into an H.G. “spiral,” as Fejzo has called it. “We probably don’t need this behavior anymore, but we haven’t evolved out of it yet, unfortunately,” she said.

Fejzo’s discovery has reshaped the field, opening up new lines of inquiry. Could GDF15’s effects be interrupted somehow? Could they be muted? Or even prevented altogether? NGM Bio, a Bay Area biotech company, is working on a new drug that would block the hormone from binding to its receptor in the brain and triggering nausea during pregnancy. (It’s unclear how expensive the drug will be; a clinical trial is under way.) Last year, Fejzo designed a study of the widely available drug metformin, which is already safely used on pregnant women with gestational diabetes and polyendocrine metabolic ovarian syndrome. The idea is that the medication will artificially raise the level of GDF15 in a woman’s blood over several months before pregnancy, allowing her to slowly adjust to the hormone and, hopefully, avoid severe symptoms. Once again, Fejzo struggled to find funding. Her application for a federal grant was denied, and she knew a pharmaceutical company wouldn’t be willing to sponsor a trial for a medication that was already so accessible.

In some ways, the hesitation among pharmaceutical companies is understandable. In the nineteen-fifties, the sedative thalidomide was marketed in dozens of countries as a treatment for morning sickness, until it became clear that it caused serious birth defects, including malformed limbs and heart and eye problems. (The medication was never approved for sale in the United States.) Thalidomide’s failure had a chilling effect on progress toward a treatment. “Pharma had no interest in developing drugs, and doctors had no interest in prescribing,” Fejzo told me.

In 2025, the journalist Carey Jones published an article in The Conversationalist titled “Let’s Fund the Damn Research Ourselves.” Jones had read about Fejzo’s work on her phone, while lying on her bathroom floor during a bout of illness in her second pregnancy. “The bathroom floor was where I spent most of my time, always within arm’s reach of a toilet,” she wrote. Her late mother had worked in women’s nonprofits, and she reached out to the organizations she remembered hearing about. She set up a crowdfunding page, and tapped alumni networks and matching programs. (One wealthy woman who had herself experienced H.G. made a significant donation.) They raised almost $1.5 million, and Fejzo’s trial began in July.

At the conference in Bergen, attendees were buzzing about metformin’s promise. In addition to Fejzo’s trial, there are two others, in the U.K. and the Netherlands, scheduled to start in the next year or so. But researchers cautioned that the drug’s efficacy has not yet been proven. It’s possible that it will work for some women but not others, or that it will provide only marginal relief, or none at all. The studies are necessary to show that the drug works. Rebecca Reynolds, a professor of metabolic medicine at the University of Edinburgh, who is running the upcoming U.K. trial, told me, “We don’t want to raise hope that this is going to cure everything.”

In some places, it may be too late for that. During one panel, we heard that a Spanish hospital was already using metformin as the standard of care for H.G. patients. Some patients have sought it out themselves. One woman, Lauren Alexander, had three difficult H.G. pregnancies before learning about Fejzo’s research. She convinced her doctor to prescribe metformin, and then took it along the lines of the trial Fejzo had designed. Alexander took the medication for six months before she became pregnant. In the early weeks, she felt a little nauseous, but nothing like what she had experienced in her previous pregnancies. She was able to keep working, and to care for her other children. Around week twelve, the nausea disappeared completely. “It felt like magic,” she told me. This past September, she gave birth to a healthy son. In Bergen, I spoke to others who said that they would consider trying it before the trials were complete. One afternoon, I sat with the red-headed midwife and a nurse, both of whom had had multiple H.G. pregnancies. “If my doctor had said, ‘Go out and eat a cup of dirt,’ I would have done it,” the midwife said bluntly. “I would have done anything to feel better.” She turned to the nurse. “Wouldn’t you?”

By a twist of fate, I had arrived at the H.G. conference in the ninth week of my second pregnancy. I felt a dull fatigue and a mild undercurrent of nausea. One morning, after my three-year-old had gone to day care, I was wiping down our sticky kitchen countertop when the smell of the cleaning solution suddenly made me retch. After I puked, I felt perversely proud, as if my nascent pregnancy—previously substantiated only by a thin pink line and a ravenous appetite—had forthrightly announced itself. “Definitely pregnant,” I thought. The friend of mine with H.G. experienced almost entirely positive reactions to her profuse vomiting from friends and family before it became clear that something was seriously wrong. Early pregnancy is so linked to illness that it’s more notable when the expecting mother has no symptoms at all.

Every pregnancy is a gamble on the health of a woman’s body, yet mothers show up to place bets again and again. In Bergen, I met women who had prepared for their pregnancies in the full knowledge that they would likely be hospitalized, unable to work, or care for their other children. I spoke to one woman over the phone who left a high-flying job on Wall Street and spent years trying to wean herself off Klonopin after having H.G., who, once recovered, went on to have another child. (She now runs a company, Phoebe, which helps women navigate pregnancy and early parenthood while working.) I spoke to another mother who had internal bleeding during one of her three H.G. pregnancies. She wanted a fourth child, but she wasn’t sure if her body could physically endure it. Still, she was considering it. “There’s a real sense of, I’m missing this human in my life,” she told me.

The conflation of pain and pregnancy can lead to a tacit acceptance of discomfort that can be hard for both patients and doctors to parse. How much pain is too much pain? The crucible of childbirth is often spoken of as transformative, the self-sacrifice of pregnancy as part of becoming a parent. People resist epidurals because they want to be present when they usher in a new life. There’s an urge to preserve something sacred and ancient, to avoid handing everything over to our brightly lit, modern world. But pregnancy is also a medical state, sometimes a dangerous and complicated one, which has been improved upon immeasurably over the years. Imagine if we treated root canals in a similar way, assuming they will always be painful, imbuing that pain with spiritual meaning, and doing nothing to address the patient’s suffering.

The conference hotel had a pool that overlooked the fjord, and women from all parts of the H.G. world—doctors, researchers, former patients—had put their swimsuits on for a dip. Some of them walked down a long path outside, and lowered themselves gingerly into the freezing waters of the fjord. Throughout the day, there had been so much talk of bodies—the ways they can fail, and turn on us, and the ways that they might be improved—but here, people seemed to wear their physicality lightly, as if they had shed several heavy layers.

In the pool, I ran into Vanover, the Indiana mom, staring out at the view. “Where I’m from, it’s all cornfields,” she said. “We don’t have anything like this.” She had never travelled alone before—she rarely left her children—but the conference organizers had sponsored her trip. In the water, she told me about being hospitalized three hours from her home during her second pregnancy. Her husband had to work, and for weeks she had no visitors. She was throwing up twenty-eight times a day, trying to keep a feeding tube down, while the doctors tried more than twenty different medications until one finally stuck. She was terrified about her daughter one day having to go through the same thing, though she was still very young. As she spoke, she grew emotional; her glasses fogged up, and tears rolled down her cheeks. “This is my therapy,” she said.

When I met with Fejzo, she told me that her children were grownups now. Her son was getting married soon, and her twin daughters were twenty-five. Her pride was evident. We were sitting in armchairs staring out at the water, a little vase of wildflowers between us. After her miscarriage, she had thrown herself into the process of finding a surrogate. “People had advised me that you don’t get over something like that until you hold the next baby in your hands,” she recalled. I asked her how often she thinks about that time. “It’s a strong memory that doesn’t go away,” she said. “But I have so many other things to think about now.” ♦