Marlena Fejzo

Vomiting and nausea are expected, if unpleasant, parts of pregnancy. But in about 2% of pregnancies, a condition called hyperemesis gravidarum (HG) causes such intense symptoms that the mother can become severely dehydrated and malnourished.

In 1999, geneticist Marlena Fejzo had such a bad case of HG that she eventually miscarried—but that didn’t stop her physician from writing off her symptoms as a cry for attention. After she recovered, Fejzo channeled her grief and rage into discovering the understudied condition’s cause, in hopes of eventually finding treatments. “I didn’t want my daughters to have to go through that,” she says. “Or anybody.”

Fejzo spent the next two decades piecing together research on HG, working around her primary job in a cancer laboratory. After years of painstaking work—and repeated rejections from research-funding agencies—she teamed up with consumer genetic-testing company 23andMe, a partnership that helped her find a gene that seemed responsible for HG. The gene controls the appetite-suppressing hormone GDF15, levels of which naturally rise during pregnancy. People with HG tend to have high levels of GDF15 during pregnancy but low levels prior to conceiving, Fejzo reported in a groundbreaking 2023 study, which suggests the condition’s debilitating symptoms happen because GDF15 levels rise after conception and shock the system.

Fejzo, who’s a clinical assistant professor at the University of Southern California’s Keck School of Medicine, hopes that either lowering GDF15 levels during, or supplementing them prior to, pregnancy could spare people with HG from the “torture” she experienced. She is currently designing studies to test her theory. This time, funding will likely come easier than it did 20 years ago. “I wasn’t able to get funding [for years because] they didn’t think I’d be successful,” Fejzo says, “which obviously was wrong.”