Researchers Discover New Genes Linked to Severe Morning Sickness During Pregnancy

Scientists may be one step closer to better treatments for severe morning sickness.

A new study published in Nature Genetics has identified nine additional genes linked to hyperemesis gravidarum (HG), the most severe form of pregnancy sickness. Researchers say the findings could help develop better treatments and may even make it possible to prevent the condition before pregnancy in women at high risk.

HG affects about 2% of pregnant women and causes extreme nausea and vomiting. Unlike typical morning sickness, it can make eating and drinking nearly impossible, leading to dehydration, weight loss, and poor nutrition. In severe cases, it can affect the health of both the mother and the baby.

Researchers from the Keck School of Medicine at USC analyzed genetic data from nearly 11,000 women with HG and more than 461,000 women without the condition, making it the largest genetic study of HG so far.

The study identified 10 genes linked to HG. While four genes were already known, six were discovered for the first time.

The strongest genetic link remained GDF15, a gene that produces a hormone that rises rapidly during pregnancy. Previous research showed that women who have lower levels of GDF15 before pregnancy may be more sensitive to the hormone, making them more likely to develop severe nausea and vomiting.

The newly discovered genes are involved in pregnancy hormones, appetite, nausea, metabolism, insulin regulation, and brain function. One gene, TCF7L2, is already known to increase the risk of type 2 diabetes and may also influence a hormone called GLP-1, which helps control blood sugar, appetite, and nausea. Researchers believe these discoveries could help explain why some women develop HG while others do not.

Current treatments do not work for everyone. The team is now planning a clinical trial to test whether metformin, a common diabetes medicine, can increase GDF15 levels before pregnancy and reduce the risk or severity of HG.

Although more research is needed, the findings offer new hope for women affected by this debilitating pregnancy condition.

REFERENCE: Marlena Fejzo, Xinran Wang, Qing Tan, et al.; Multi-ancestry genome-wide association study of severe pregnancy nausea and vomiting. Nature Genetics, 2026; 58 (4): 810 DOI: 10.1038/s41588-026-02564-4