Nausea and vomiting, common in early pregnancy, are primarily caused by a single hormone, according to a study published Wednesday in the journal Nature. Researchers said the discovery could lead to better treatments for morning sickness, including in rare cases of life-threatening morning sickness.
The study confirms previous research that pointed to a hormone called GDF15. Researchers found that the amount of hormones circulating in a woman’s blood during pregnancy, as well as her exposure to the hormones before pregnancy, influenced the severity of her symptoms.
More than two-thirds of pregnant women experience nausea and vomiting during the first trimester. Additionally, about 2% of women are hospitalized with a condition called hyperemesis gravidarum. Hyperemesis gravidarum causes vomiting and nausea throughout pregnancy. This condition can lead to malnutrition, weight loss, and dehydration. It also increases the risk of premature birth, preeclampsia, and blood clots, which can be life-threatening for mother and fetus.
Perhaps nausea and vomiting are so common during pregnancy that doctors overlook it and dismiss its severe symptoms as psychological, even though it is a major cause of hospitalization in the first trimester. Experts say that often. Although celebrities such as Kate Middleton and Amy Schumer have raised the profile of the condition in recent years by sharing their own experiences, it remains poorly researched.
“I’ve been working on this problem for 20 years, and there are still reports of women dying from this disease and women being abused,” said co-investigator and geneticist at the Keck School of Medicine at the University of Southern California. says Dr. Marlena Fezo. -Author of new study.
She knows firsthand the pain of this disease. During her second pregnancy in 1999, Fezo could not eat or drink without vomiting. She rapidly lost weight and became so weak that she could no longer stand or walk. Her doctor was negative, wondering if she was exaggerating her symptoms to get attention. She was eventually hospitalized and suffered a miscarriage at 15 weeks.
Fezo said she asked the National Institutes of Health to fund genetic research for hyperemesis, but was denied. Still, she persuaded her popular genetic testing company, 23andMe, to include a question about hyperemesis in a survey of tens of thousands of customers. In 2018, she published a paper showing that patients with hyperemesis tend to have mutations in the GDF15 gene.
Hormones are chemicals that send messages throughout the body. GDF15 is released by many tissues in response to stress such as infection. And that signal is very specific. Receptors for this hormone are concentrated in parts of the brain that make you feel sick and vomit.
In the new study, Fejzo and colleagues at the University of Cambridge in the UK measured hormones in the blood of pregnant women and analyzed genetic risk factors for hyperemesis.
Researchers found that women experiencing hyperemesis had significantly higher GDF15 levels during pregnancy compared to women without symptoms.
However, hormonal effects appear to depend on the woman’s susceptibility and pre-pregnancy hormone exposure. Researchers found, for example, that Sri Lankan women with a rare blood disorder that causes chronically high levels of GDF15 rarely experience nausea or vomiting during pregnancy.
“This completely eliminates the nausea. They have very few symptoms during pregnancy,” said Dr. Stephen O’Rahilly, an endocrinologist at the University of Cambridge who led the study.
Dr. O’Rahilly hypothesized that long-term exposure to GDF15 before pregnancy may have a protective effect, making women less susceptible to the surge in hormones caused by fetal development.
In a laboratory experiment, researchers exposed several mice to small doses of the hormone. When given a larger dose three days later, the mice did not lose their appetite as much as animals not given earlier, showing a strong desensitizing effect.
Experts said the findings offer hope for better treatments for hyperemesis. Patients with hyperemesis could someday be able to take a drug that blocks the hormone’s effects in the brain, if clinical trials confirm that the drug is safe during pregnancy. Such drugs are being tested in clinical trials with cancer patients who also suffer from anorexia and vomiting due to their GDF15.
It may also be possible to prevent symptoms. At-risk women, such as those who have experienced severe nausea or vomiting during a previous pregnancy, may be exposed to low doses of the hormone before pregnancy. (One of her diabetes medications, metformin, increases her GDF15 levels and is already prescribed to increase fertility in some patients.)
Rachel Freesey, a geneticist at the University of Exeter who was not involved in the study, said the new study was strong because it provided genetic evidence for a causal link between GDF15 and the disease. She says doing so will further raise awareness of the disease.
“There’s kind of an assumption that a lot of people have that women should be able to handle this situation,” Freesey said. This biological explanation would “further strengthen the belief that this is real and not just something in someone’s head,” she said.