My “morning sickness” started in the evening. That was the first clue the antenatal guides and obstetric textbooks were not telling women the whole truth. When the nausea lasted all day, and then for 245 days, that was the second clue. If I’d known then that I would feel sick until my baby was born, I’m not sure I would have braved pregnancy at all.

A fortnight after I saw those two pink lines, I started to feel unwell. Blaming a rushed dinner after getting home late from the hospital – I was a junior doctor at the time, and still am – a tightness lodged itself where my bottom ribs meet my stomach. By morning, I felt hungover, though I hadn’t touched alcohol in weeks. At a patient’s bedside, I suddenly tasted something sour. I ran to the ward sluice. Holding my hair back from my face, I cried out in shock at how violently I was sick. Food and then acid and then air. Leaning against the wall, my knees fizzing, I wiped my mouth with a paper towel that absorbed almost nothing. It was the last time I would be at work for more than two months.

Pregnancy is not a disease. Expectant mothers are not patients. But that doesn’t mean common symptoms are not pathological. Up to 90% of pregnant women feel sick and 35% may need clinical help for their nausea and vomiting.

At medical school, hyperemesis gravidarum was covered in a slide or two. I remember hoping it would never happen to me. Known to its victims as HG, hyperemesis is “excessive” sickness. It’s thought to affect 2% of pregnant women. This statistic excludes many whose days are punctuated by nausea, retching and vomiting, but never find the diagnosis or support they need. Even using this conservative estimate, of the 700,000 women who give birth each year in the UK, 14,000 will have hyperemesis.

After premature labour, vomiting is the second most common reason for any pregnant woman to need a hospital bed. The damage can be horrific: eardrums burst; gullets bleed; critical dehydration; vitamin stores ransacked; urine contains ketones, a marker of starvation. To assess severity, clinicians use a tool whose name sounds like tone-deaf misogyny: the PUQE (pregnancy-unique quantification of emesis).

Meanwhile, parents are offered reassurance that their babies are doing just fine. Medicine’s story of the foetus as “parasite” offers a soothing idea that this scavenger will take whatever it needs from its host. But a study published in 2021 shows a five-fold increased risk of small-for-gestational-age babies from mothers who have HG, a more severe effect on size than maternal amphetamine, cannabis or tobacco use. In these children, there are higher rates of autism, mental health problems and neurodevelopmental delay. Some foetuses never reach this stage. Up to one in seven women with hyperemesis resorts to an abortion, cruelly called a “therapeutic termination”, while more than 50% consider it. These are wanted, beloved babies.

Ask a doctor why nausea and vomiting start in the first trimester, why hyperemesis may continue for months, and why it recurs in over 75% of future pregnancies, and they may look shifty. Why is women’s health so low on the agenda that these extreme symptoms are diminished, poorly treated and misunderstood?

“My body kills babies,” said Dr Marlena Fejzo, sitting in her Los Angeles home, sun streaming through the half-closed blinds. In 1999, she was a post-doctoral student working at UCLA, studying genetic markers of multiple sclerosis. Then she became pregnant. In the early weeks she was vomiting so forcefully her doctor arranged for IV fluids to be administered at home, while an anti-sickness medication, ondansetron, was pumped into her veins on a four-hourly basis. Even this powerful drug, originally developed for patients receiving chemotherapy, didn’t touch her symptoms. Fejzo’s retired parents came every day to provide nursing care, clean bedpans and diligently test her urine for ketones. Fejzo’s bones began to dig into the mattress. The slightest turn of her head started a spiral of vomiting. After 10 weeks in bed, she started bleeding and lost the baby.

It was a tragedy that became a calling. “The severity of hyperemesis is just not understood unless you’ve been through it yourself,” says Fejzo. “The only way people who haven’t had it can understand it is if they think about the time when they’re over the toilet. Those 30 seconds before a person vomits and thinks they’re about to die. That is how women with HG feel all the time.” Fejzo returned to work in the lab six weeks later, traumatised at losing her daughter, but resolute that she would spare other women this pain. “I want to do a genetic study on hyperemesis gravidarum,” Fejzo announced at a team meeting. “I want to find its cause.” Her boss laughed.

I did breathing exercises. I bought a miniature Tens machine to wear on the nei guan pressure point on the inside of my wrist. I ordered every ginger product I could find (Ginger tea! Ginger biscuits! Ginger boiled sweets!) Each tincture and hack failed. I called my GP to tell her I wasn’t functioning. Vomiting wasn’t the worst part – I was saturated with nausea. I was prescribed a brown glass bottle of white tablets. She was kind, suggested I take the cyclizine and wrote me a sicknote for a fortnight. I finally went back in person, self-conscious about vomiting in public. I explained my situation to a different doctor. He insisted on three antiemetics simultaneously: cyclizine, prochlorperazine, and ondansetron.

When I said I was wary of more drugs, he told me to “disengage my academic brain”. But I had read a paper linking ondansetron with foetal cleft lips and palates. The European Medicines Agency advised against its use in the first trimester. This was unfortunate, as ondansetron is the most effective drug for pregnancy sickness from a slim range of poor options, helping symptoms in half of women. The association between ondansetron and oral clefts is, in fact, minute. There is a 0.03% increase in risk compared to babies not exposed to ondansetron. That’s an additional three clefts per 10,000 births. But as I held the prescription, I could not see these numbers in the way I would as a doctor. I was yet another lost patient. My trust that medication could keep both me and my baby safe dissolved.

As with so many drugs, antiemetics like ondansetron and cyclizine are not licensed for use in pregnancy and, when prescribed, patients carry the risk. In the late 1950s and early 1960s, thalidomide was given off-licence to treat pregnancy sickness. Within two years, the medication’s appalling effects on skeletal development in the first trimester became clear when babies were born dead or with stunted limbs.

Researchers and pharmaceutical companies had been burnt. Pregnant women have since found themselves excluded from drug trials and, therefore, from the evidence base such trials produce. But these results are essential to guide, protect and reassure them.

I was convinced that my baby’s safety was more important than my suffering. I realise now that our needs could not be so easily separated. My body was the place where she and I both lived, and it would leave its mark on her, too. I returned to work in the middle of my second trimester when I had stopped vomiting throughout the day. The nausea, however, was constant. My salary had been halved. If I wasn’t at work, I would endanger my maternity leave pay. I was due to start a job in obstetrics. Here, I hoped for understanding. But patients with HG were a low priority. They had to pass the toast test to be discharged home – keep down a slice without bringing it back up. Dry white triangles lay nibbled or untouched on trays. “Nearly half the women on the ward have hyperemesis,” I said flintily to one of my seniors. “Isn’t there anything else we can do for them?”

“What you need to remember about hyperemesis,” she said, “is that most of it is…” She pointed her index finger towards the side of her forehead, tracing circles in the air, and then planted her fingertip firmly on her temple. I hadn’t seen that gesture since school. They’re mad, these women. Her hand said everything she knew not to say out loud. “Did you not feel sick when you were pregnant?” I asked. “The less I worked, the worse it was. I operated through it,” she replied. She picked up her phone. The conversation was over.

The exchange reminded me of a recorded lecture I’d been sent by a medical student two years previously when I was researching obstetric safety in the US. I found the email attachment again.

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“This is usually what we see in people with hyperemesis,” the clinician tells her audience, looking out at a sea of laptops. “They are so severe they have to be admitted to hospital. There’s usually some psychosocial thing going on. Either they don’t want to be pregnant or they don’t have support at home. Or some situation like that.” Then the kicker: “And they often don’t want to feel better.”

I couldn’t shake the brutality of this idea as I walked to my car that evening, stroking my bump. I wanted, more than anything, to be pregnant. I resented my body, though. How dare it do this to us? How dare it not be able to cope?

As Dr Fejzo searched for the cause of hyperemesis, she knew that for many experts the answer was already settled: it’s all in women’s heads. Medicine tends to distrust symptoms that are hard to diagnose, hard to measure, and hard to treat. Nausea is all three.

When “pernicious vomiting of pregnancy” was first described in medical literature by the French obstetrician Paul Dubois in 1852, hysteria was being used to explain away many female complaints. A collection of scholarly articles from 1980 reports that “since Freud called our attention to the psychological meaning of vomiting”, hyperemesis is evidently a “symbolic rejection of the child or an oral attempt of abortion”. Pregnancy sickness afflicted people who didn’t want to be mothers after all.

But vomiting women are also told to be cheerful. Paul Sherman, a professor of neurobiology at Cornell University, views sickness as an “evolutionary wellness insurance” which prevents mothers from eating toxic food while their baby’s organs are forming. Pregnant women still encounter this way of thinking at their scans. Vomiting is interpreted as an early sign of a healthy pregnancy. Through hushed darkness, the sonographer asked me how I was feeling. I didn’t hold back. “Oh good,” she beamed, “that’s what we want to hear.”

The cause of pregnancy sickness has also been hypo-thesised. Beta human chorionic gonadotropin (ß-hCG), a pregnancy hormone produced by the placenta, rises rapidly in the first trimester, then falls from around 10 weeks’ gestation. At this point, for some, nausea and vomiting may start to ease. But any causal link is conjecture. The ß-hCG theory is nevertheless the explanation presented in textbooks.

Reacting against science built on prejudice rather than proof, Fejzo started studying hyperemesis after clocking off from her day job. She was confident that women’s DNA would provide answers to validate the disease that had cost her so much. First, she needed to establish that HG runs in families. By 2016, she had surveyed and studied more than 4,400 pregnant women in the US and across the world to confirm that it did. She then took saliva samples from HG sufferers and compared them to samples from unaffected women. She designed a “genome wide association study” in which individuals’ genomes are scanned and contrasted. Having been rejected by academic funders, Fejzo’s project finally found an industry partner in the genetic testing company 23andMe.

In 2017, the results came in, and a second study, published last month, confirmed the findings. Fejzo’s work shows no association between hyperemesis and hCG genes, discrediting the old medical orthodoxy. But another gene that codes for a nausea and vomiting hormone – GDF15 – is implicated.

GDF15 is expressed at its highest levels in the placenta, and in other organs at lower levels which increase in response to physical stress, such as a heart attack or infection. The hormone also contributes to cachexia, the profound weight loss and muscle wasting seen in cancer patients, which can lead to death. Cachexia symptoms are eerily mirrored in women with hyperemesis. But blood concentrations of GDF15 in hyperemesis may be three times higher than those seen in cancer cachexia.

“When cancer patients say they feel like they’re dying, they’re believed,” says Fejzo. “But when hyperemesis patients say they feel like they’re dying – and they may feel three times as bad as the cancer patients with respect to nausea and vomiting – they really need to be taken seriously.”

Phase 1 trials are currently under way to treat cachexia by giving cancer patients a medication that neutralises GDF15. Thanks to Fejzo’s discovery, this same drug might one day be a lifeline for pregnant women and their babies.

My own sickness lifted as a roaring, blood-stained, adored newborn was raised over the green surgical drape to meet her parents. I was euphoric that my daughter was well – and that I was free.

She can now say “umbrella”, point at the moon and show off her stubby teeth. In the bath, I look at the fading smile of my caesarean scar, silvery at the edges, but still angry and purple in the middle.

The biological clock’s alarm is often assumed to be sounding loudly for mothers who have a toddler. But until we are believed, involved in decision making about medication options, presented with reliable evidence, given permission to feel awful for however long it takes not to, and supported through what could be the hardest months of our lives, I’ll pause when well-meaning people ask when, not if, I’m going to have another baby.

For support and information on hyperemesis gravidarum, HER Foundation is the world’s largest grassroots network of HG survivors and experts (hyperemesis.org)