Scientists Find Six New New Genetic Links Behind Severe Morning Sickness

Scientists have identified six new genetic links behind extreme morning sickness.

In the largest genetic study of hyperemesis gravidarum (HG) to date, a research team from the Keck School of Medicine of the University of South Carolina and international collaborators analyzed genetic data from nearly half a million women.

The study, published in Nature Genetics, examined 10,974 women who experienced HG and compared them with 461,461 controls across European, Asian, African and Latino ancestries.

Newsweek reached out to the Keck School of Medicine of USC for comment via email.

HG affects about two percent of pregnant women and is marked by relentless nausea and vomiting so severe that eating and drinking can become extremely difficult.

In extreme cases, the condition can lead to dehydration, malnourishment and hospitalization, putting both mother and baby at risk.

The new findings build on earlier work led by USC researcher Marlena Fejzo, Ph.D., who previously identified the gene GDF15 as a key driver of pregnancy sickness.

In the latest study, researchers confirmed GDF15 as the strongest genetic link to HG and identified nine additional associated genes, six of which had never before been tied to the condition.

“Because this is the largest study of HG ever conducted, we've been able to tease out important new details that were previously unknown,” said Fejzo, a clinical assistant professor of population and public health sciences at USC.

She added that including women from multiple ancestry groups increases confidence that the findings apply broadly, not just to one population.

The 10 genes linked to HG include four previously identified ones: GDF15; its receptor gene GFRAL; and IGFBP7 and PGR, both involved in placental development.

Prior research showed that sensitivity to the hormone GDF15 plays a crucial role. Women with lower exposure to GDF15 before pregnancy-often because of genetic variants-appear more vulnerable to severe nausea, while higher pre-pregnancy exposure may protect against intense symptoms.

Among the six newly identified genes, one stands out: TCF7L2, one of the strongest genetic risk factors for type 2 diabetes and a gene also associated with gestational diabetes.

Researchers suspect it may influence GLP‑1, a gut hormone involved in blood sugar regulation, appetite and nausea, though its exact role in pregnancy remains unclear.

Other newly implicated genes are tied to appetite regulation, nausea signaling, insulin and metabolism, and brain plasticity-the way the brain learns and adapts.

Fejzo suggested the brain may form strong food aversions during pregnancy by learning to associate certain foods with feeling sick, a theory that requires further study.

The researchers also found overlap between HG-linked genes and other pregnancy complications, including shorter gestation, lower birth weight and preeclampsia.

Despite available treatments, options remain limited. Even Zofran, one of the most commonly prescribed medications, only partially relieves symptoms in about half of patients. The genetic discoveries point to new treatment pathways and raise the possibility of tailoring therapies based on a woman's genetic profile.

Fejzo's team has now received approval to launch a clinical trial testing metformin, a common diabetes medication known to raise GDF15 levels.

The trial will explore whether taking metformin before pregnancy could reduce sensitivity to the hormone and lower the risk or severity of HG for women with a prior history of the condition.

Newsweek's reporters and editors used Martyn, our Al assistant, to help produce this story. Learn more about Martyn.

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This story was originally published April 14, 2026 at 5:00 AM.