Largest Pregnancy Sickness Study Reveals New Genetic Links to Hyperemesis Gravidarum

What Did the Largest Pregnancy Sickness Genetic Study Find?

A research team led by the University of Southern California has conducted the largest genetic study of pregnancy sickness to date, uncovering six new genetic links to hyperemesis gravidarum (HG) — a debilitating condition characterized by severe nausea, vomiting, and dehydration that can require hospitalization. The findings build on the same team's groundbreaking 2023 research, published in Nature, which identified the gene encoding the hormone GDF15 as a key driver of pregnancy-related nausea.

GDF15, or growth differentiation factor 15, is produced by the placenta during pregnancy. The 2023 study, led by Marlena Fejzo and colleagues, demonstrated that women with higher sensitivity to GDF15 — or whose placentas produce unusually high levels of the hormone — are more likely to develop severe pregnancy sickness. The new study extends this work by mapping additional genetic pathways that influence how the body produces, signals, and responds to GDF15 and related molecules, suggesting the condition involves a more complex biological network than previously understood.

Why Is Hyperemesis Gravidarum So Difficult to Treat?

Hyperemesis gravidarum affects an estimated 0.3% to 3% of pregnancies worldwide, depending on diagnostic criteria. Unlike typical morning sickness, which affects up to 80% of pregnant women to some degree, HG involves persistent vomiting that can lead to weight loss, dehydration, electrolyte imbalances, and in severe cases, hospitalization or pregnancy termination. Despite its significant impact, the condition has historically received limited research attention, and existing treatments — primarily anti-emetic drugs and intravenous fluids — address symptoms rather than underlying causes.

The identification of GDF15 as a central mechanism has been a turning point. Researchers have proposed that pre-pregnancy exposure to GDF15 could desensitize the body's response, potentially preventing severe symptoms. The newly discovered genetic variants offer additional therapeutic targets and may help explain why some women develop HG while others with similar GDF15 levels do not. Understanding these genetic modifiers could eventually enable clinicians to identify high-risk women early in pregnancy and offer targeted interventions before symptoms become severe.

What Could These Findings Mean for Future Treatment?

The expanded genetic map of hyperemesis gravidarum opens several promising research directions. First, the identified variants could form the basis of a genetic risk score, allowing healthcare providers to flag women at elevated risk for HG before or early in pregnancy. Early identification could enable proactive management strategies, including dietary modifications, early anti-emetic therapy, and closer monitoring.

Second, the new genetic targets may accelerate drug development. Since the 2023 GDF15 discovery, pharmaceutical researchers have been exploring ways to modulate GDF15 signaling. The additional genes identified in this study point to related but distinct biological pathways, potentially broadening the range of druggable targets. While clinical applications remain years away, the research represents a fundamental shift in how the medical community understands pregnancy sickness — from a condition once dismissed as psychological to one with clear, measurable biological underpinnings rooted in genetics and hormone signaling.