For a long time, hyperemesis gravidarum was treated as an exaggerated version of morning sickness, something women were expected to manage or endure quietly. Hyperemesis gravidarum, or HG, doesn’t just cause nausea in the first trimester. It can mean relentless vomiting, dehydration, weight loss, electrolyte imbalances, hospital visits and days when even a sip of water feels impossible. It is one of the leading causes of hospitalization in early pregnancy and, in severe cases, can lead to malnutrition and dangerous complications.
Now, one of the largest genetic studies ever done on HG adds more evidence to what patients and experts have been saying for years: it’s a serious biological disease, not a psychological weakness. In the new multiancestry study published in Genetics of Natureresearchers analyzed genetic data from 10,974 women with HG and 461,461 controls of European, Asian, African, and Latino descent. They identified 10 genetic associations associated with severe nausea and vomiting of pregnancy, including six newly identified loci: SLITRK1, SYN3, IGSF11, FSHB, TCF7L2 and CDH9.
This matters because HG has been minimized very often. The condition affects around 2% of women and while that may sound small on paper, the impact can be huge. HG can make eating almost impossible. It can disrupt work, care and mental health. It can leave pregnant women feeling weak, isolated and afraid. It can also put both mother and baby at risk when the body doesn’t get enough fluids, calories or nutrients. Researchers and clinicians note that complications can include significant weight loss, orthostatic hypotension, ketonuria, electrolyte imbalance, and nutritional deficiencies such as Wernicke encephalopathy.
One reason this study stands out is that it builds on a major discovery by the same research team. In 2023, researchers linked the hormone GDF15 to nausea and vomiting in pregnancy and to HG, showing that both fetal production of the hormone and maternal sensitivity to it play an important role. They found that higher levels of GDF15 in maternal blood were associated with vomiting in pregnancy and HG, and that women with lower exposure to GDF15 before pregnancy may be more vulnerable because they are more sensitive to the hormonal surge that accompanies pregnancy.
The new study reinforces this idea. Among the 10 gene signals revealed, GDF15 remained the strongest. But the bigger story is that HG doesn’t seem to be driven by a single path. The newly implicated genes show systems involved in pregnancy hormones, appetite regulation, nausea, insulin signaling, metabolism, brain plasticity, and placental biology. The researchers also reported that some of these HG-linked loci were associated with other pregnancy characteristics and outcomes, including abnormal pregnancy weight gain, length of pregnancy, birth weight, and preeclampsia.
This explains why HG can feel so consuming. This is not just a “sensitive stomach”. It appears to involve a deeper biological cascade that affects how the body and brain respond to pregnancy itself. One of the most interesting genes highlighted in the study is TCF7L2, a gene already known to be a strong risk factor for type 2 diabetes and also linked to gestational diabetes. Researchers say it may affect GLP-1, a hormone involved in controlling blood sugar, appetite and nausea. In other words, this research opens the door to the possibility that severe pregnancy disease is linked to broader metabolic and signaling pathways than previously understood.
There is also something deeply validating about these findings. HG has historically been misunderstood, and many patients have described being dismissed, doubted, or told it was stress, anxiety, or just part of pregnancy. Modern reviews now make it clear that while anxiety and depression may coexist with HG, they are more likely to be consequences of the disease than its cause, and most women with HG do not have a pre-existing psychological disorder. This distinction matters. When a person is repeatedly vomiting, losing weight, unable to function, and cycling through medical appointments without relief, disbelief adds another layer of damage.
This study doesn’t mean doctors can yet run a quick genetic test and predict exactly who will develop HG or how severe it will be. But it brings the field closer to that future. It also points researchers to better treatments. Currently, available drugs help some patients, but not enough. The USC press release notes that even ondansetron can only provide partial relief in about half of patients. The team also received approval to start a clinical trial of metformin, a widely used diabetes drug that increases GDF15 levels, to test whether taking it before pregnancy can reduce nausea and vomiting or help prevent HG in women with a previous history of the condition. A registered trial for this question is now listed on ClinicalTrials.gov.
This may sound surprising at first. Why study a diabetes drug for severe pregnancy sickness? The answer goes back to the history of GDF15. If susceptibility to HG is shaped in part by how much exposure a woman has to GDF15 before pregnancy, then raising baseline levels beforehand could potentially help the body adjust when pregnancy causes an increase in GDF15. It’s still a case-by-case, not standard care, but it shows how genetic discoveries can lead to practical next steps instead of dead ends.
For families, the most important takeaway may be the simplest: severe pregnancy illness is real and can be dangerous. HG is not something a person has to “harden” on their own. When vomiting becomes persistent, when fluids do not stay low, when weight drops, or when dizziness and weakness occur, this is a medical issue that deserves immediate attention. Research like this is important not only because it may lead to better drugs, but because it continues to push medicine and the public to take HG as seriously as patients have long needed.
Pregnancy starter kit
This post contains affiliate links through which we will receive a small percentage if you purchase through the link.
