Approximately 70% of pregnant individuals experience morning sickness, which includes nausea and vomiting at any time of the day, not just in the morning. This can disrupt their eating habits and frequently sends them to the bathroom. While this typically eases after the first trimester, it can, in some cases, persist throughout the pregnancy.

A small percentage, up to 3% of pregnant individuals, endure a severe and potentially life-threatening form of morning sickness known as hyperemesis gravidarum (HG). This condition severely impacts their ability to retain food and liquids, leading to significant dehydration and often necessitating hospitalization. Notable individuals such as Catherine, the Princess of Wales (formerly known as Kate Middleton), and comedian Amy Schumer have suffered from HG.

Marlena Fejzo, an assistant professor of population and public health sciences at the University of Southern California’s Keck School of Medicine, has been recognized with the BioInnovation Institute & Science Translational Medicine Prize for Innovations in Women’s Health for her research on the genetics of HG. Fejzo, who has personally battled HG, expressed in an award essay, “We have managed to send men to the moon decades ago, yet women continue to die from severe nausea and vomiting during pregnancy.”

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Fejzo’s interest in HG was sparked by her own severe experiences with the condition during her pregnancies. In collaboration with the consumer genetics company 23andMe, she led a study that pinpointed two genes associated with HG: GDF15 and IGFBP7.

In a 2023 study published in Nature, Fejzo and her team confirmed that the hormone GDF15, which is regulated by the GDF15 gene, plays a crucial role in HG and less severe cases of morning sickness. Typically, GDF15 is produced in response to physical stress. However, individuals with HG have a variant of the gene that results in lower hormone levels, exacerbating their symptoms during pregnancy due to high levels of GDF15 produced by the placenta.

Currently, Fejzo is exploring potential treatments for HG, including the diabetes medication metformin and more specific antibody treatments.

Scientific American discussed the challenges and advancements in treating hyperemesis gravidarum with Fejzo, including the discovery of the GDF15 gene’s role.

[An edited transcript of the interview follows.]

What is hyperemesis gravidarum?

Hyperemesis gravidarum is an extreme form of morning sickness that disrupts normal eating and drinking habits, leading to dehydration, weight loss, and often requires IV fluids to manage dehydration and electrolyte imbalances. It commonly requires hospitalization and is a major reason for hospital admissions in early pregnancy. Despite its prevalence, surprisingly little is known about the condition.

After suffering from HG herself, Fejzo became dedicated to uncovering its causes. She collaborated with Kimber MacGibbon, director of the Hyperemesis Education and Research Foundation, to explore whether HG had genetic roots. Their research revealed a significant familial risk and led to a genetic study that identified specific genes associated with HG.

Fejzo’s findings indicated a strong link between HG and the hormone GDF15. Further genetic analysis revealed mutations in the GDF15 gene that significantly increased the risk of HG. This insight was crucial in understanding the biological mechanisms behind HG and has opened the door to potential new treatments.

Fejzo is also investigating the evolutionary reasons behind elevated GDF15 levels during pregnancy, suggesting it may have been a protective mechanism in ancient times to avoid risks during food gathering. Despite its historical benefits, this response may no longer be necessary in modern humans, indicating a potential area for therapeutic intervention.

Current research into treatments for HG includes studying the effects of metformin and developing new medications that target GDF15 pathways. Fejzo’s ongoing work offers hope for more effective treatments in the near future.