Scientists Uncover Nine New Genes Behind the Most Severe Form of Pregnancy Sickness

A sweeping genetic study has identified nine new genes tied to hyperemesis gravidarum, the debilitating extreme form of pregnancy sickness that can leave expectant mothers unable to keep down food or water, bringing the total number of known risk genes for the condition to ten.

The research, led by scientists at the Keck School of Medicine of the University of Southern California and published in the journal Nature Genetics, is the largest of its kind ever conducted. Investigators carried out a multi-ancestry genome-wide association study comparing 10,974 women who suffered hyperemesis gravidarum against 461,461 women who did not, drawing on participants of European, Asian, African and Latino descent to make the findings broadly applicable.

The analysis confirmed GDF15 — a gene that encodes a hormone involved in nausea and appetite — as the strongest genetic link to the condition, echoing earlier work that first implicated the hormone. But it also surfaced nine additional associated genes, six of which had never before been connected to the illness. Several of the newly identified genes are involved in appetite regulation, nausea, metabolism and brain function, sketching a biological portrait of a disorder that has long been dismissed or misunderstood.

Hyperemesis gravidarum is far more serious than the queasiness many women experience in early pregnancy. It can cause severe dehydration, dangerous weight loss and repeated hospitalizations, and in some cases leads women to terminate otherwise wanted pregnancies. For generations it was often waved away as psychological or as something sufferers should simply endure, a stigma that slowed scientific understanding and left patients with few effective treatments.

By pinpointing the genes and biological pathways at work, the study opens the door to more targeted therapies aimed at the root causes rather than just the symptoms. Because the GDF15 hormone appears central, researchers are increasingly interested in whether blocking or modulating its signaling could prevent the worst nausea — and even whether women at genetic risk might one day be treated before symptoms spiral.

The findings also carry a broader message about women's health research, a field that scientists say has historically been underfunded relative to the toll such conditions take. For the many women who have suffered through hyperemesis gravidarum in silence, the identification of concrete genetic drivers reframes the illness as a biological condition with measurable causes — and, potentially, a treatable one. The study also underscores how genetics can validate patient experience: for women repeatedly told their suffering was exaggerated or self-inflicted, the discovery of specific inherited risk factors offers not just the promise of better drugs but a measure of long-denied medical recognition. Larger trials will now be needed to translate the genetic map into treatments that can be safely used during pregnancy.