No, severe morning sickness is not ‘harmless’ or ‘normal’

When in 1999 at 31, geneticist Marlena Fejzo was pregnant for the second time and expecting some of the nausea that affects about 70 per cent of pregnancies, she didn’t expect to be so flattened by it that she couldn’t eat or drink.

Her GP suggested that she was exaggerating her symptoms to get attention and, though he said she needed a feeding tube, it was too late. She had become so weak she had lost the baby.

It might be an evolutionary adaptation, but severe morning sickness is not normal or harmless.Credit: Getty Images

Twenty-five years later, Fejzo, now a mother of three, is a world-leading researcher in morning sickness and she is one of Time magazine’s Women of the Year.

Her previous research found that “morning sickness” during pregnancy is the result of a spike in the levels of a stress response hormone called growth and differentiation factor 15 (GDF15).

In a paper published in Nature in 2023, Fejzo and an international research team found that women who are genetically predisposed to low levels of GDF15 before pregnancy can become hypersensitive to its rapid rise during pregnancy, leading them to experience severe morning sickness, otherwise known as hyperemesis gravidarum (HG).

Moreover, the levels of GDF15 are significantly higher if the mother is carrying a female fetus: about 72 per cent of women report nausea, versus about 42 per cent who are carrying a male.

And if the fetus carries the mutation that leads to the GDF15 hypersensitivity, the mother is less likely to experience HG. But when the fetus does not have the mutation, the mother does experience HG, which explains why women can have it in some pregnancies but not others.

Now, in a new editorial published in the journal Trends in Molecular Medicine, Fejzo says severe morning sickness, which she says is essentially a form of starvation, is neither “normal” nor “harmless” as she debunks common myths and explores possible treatments.

An adaptive response that is no longer helpful

Morning sickness, which is often not limited to the morning, is likely a protective evolutionary adaptation that helped to prevent mothers from eating foods that might harm the developing fetus, Fejzo says.

Marlena Fejzo: “Until modern times, finding food was fraught with risks.”Credit: The HER foundation

Given animals that lay eggs such as snakes and octopuses display symptoms of nausea and appetite loss as well, it may have also evolved to prevent mothers-to-be venturing out into a hostile environment of predators, pathogens and extreme weather.

She recounts a snake study that revealed that aspic vipers stop hunting during gestation: 12 per cent refuse to eat a mouse placed directly in front of them; and octopuses care for their eggs without eating, eventually starving to death.

“Until modern times, finding food was fraught with risks,” writes Fejzo, of the Centre for Genetic Epidemiology at the University of Southern California. “Genes that encode a behaviour that results in avoiding those risks in lieu of nutritional needs likely provide some survival advantage.”

While those risks may still exist in the wild, they no longer exist for humans.

The risks of severe morning sickness, which is associated with poor outcomes for mother and baby and can be life-threatening, are now far greater: “The condition likely gave an evolutionary advantage in the wild that is now superfluous for humans.”

Physical, emotional risks

HG, experienced by at least 3 per cent of pregnant women, is associated with an array of health risks for the mother and baby.

These include a nearly three-fold risk of the baby being born before 34 weeks and, later in life, a 25 per cent higher risk of depression and social problems as well as a greater likelihood of being diagnosed with autism spectrum disorder, ADHD, childhood cancer and respiratory and cardiovascular disease.

This is in part due to nutritional deficiencies, but also because women can feel so unwell that they miss routine screenings and appointments, says Dr Sarah Livingstone, a staff specialist in obstetrics and gynaecology at the Royal Hospital for Women in Sydney.

Biochemical changes and altered metabolism may also put them at risk of a range of diseases, she says.

Severe morning sickness is also a top predictor of postnatal depression: 26 per cent of those with HG report suicidal ideation and 18 per cent experience post-traumatic stress disorder.

“The psychosocial part of it is horrible. It’s really debilitating,” says Livingstone. “They can’t work, they can’t socialise with their friends, they can’t look after their own kids because they feel so sick.”

It means a percentage of women choose not to have another child or request a termination if they do become pregnant because they are afraid of going through it all again, she says.

The fact it is not well understood and that it is often dismissed as a normal part of pregnancy just compounds the sense of isolation and not being validated, says Centre of Perinatal Excellence executive director Dr Nicole Highet.

COPE recently conducted a survey of women who have HG and found 60 per cent didn’t feel they had support or understanding from those around them. Not only does this affect their relationships, says Highet: “They give up going to others about it.”

Old and new remedies

The current approach in many hospitals involves “really old-school treatment”, says Livingstone.

This includes prescribing supplements such as iron, vitamins K and B1 and folic acid, antiemetic medication and electrolytes as well as admitting women to hospital for IV fluids.

Specialists also often recommend eating dry crackers, having small meals, consuming oral ginger, trying acupuncture and aiming to keep a routine where possible.

“Dehydration and undernutrition can lead to increases in GDF15 due to organ stress, so do your best to stay hydrated and keep a balanced diet,” says Fejzo via email. “And if you can’t tolerate prenatal vitamins, try part of a vitamin or cereals or other foods supplemented with vitamins.”

Though this can help to keep the worst of it at bay, it’s imperfect, and many practitioners remain hesitant to treat morning sickness, fearful of repeating the Thalidomide tragedy, says Dr Julie Sartori, of the Placenta Project at Edith Cowan University.

Plus, she says, there is no standard medication recommended by the Therapeutic Goods Administration. “This means it is left up to practitioners to decide what is provided,” Sartori says.

The findings around GDF15, however, are “very significant”, she says. They will be important for the future treatment of severe sickness during pregnancy but more research is needed.

Eventually, Fejzo hopes to end the suffering of severe morning sickness completely.

She is testing different approaches including lowering GDF15 signalling during pregnancy or raising GDF15 levels before pregnancy to decrease the woman’s sensitivity to it during pregnancy. One possibility for this is metformin, a drug known to increase circulating GDF15 levels.

While these tests are in the works, there are resources that can help. COPE has designed a free app that helps to guide and support mums and their partners through pregnancy, including HG.

Fejzo also recommends visiting hyperemesis.org and taking the HELP score to assess your nausea and vomiting level.

“Some people don’t know when their symptoms are not normal and that they may need medical attention,” she says.

Make the most of your health, relationships, fitness and nutrition with our Live Well newsletter. Get it in your inbox every Monday.