New Study Reveals Cause of Morning Sickness

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Dec. 14, 2023 – Most pregnant people have nausea and vomiting, sometimes to a life-threatening degree. Researchers have now discovered why, and their new study in the renowned journal Nature suggests prevention and treatment options.

The cause of what is commonly referred to as “morning sickness” is due to the pregnant person’s sensitivity to a hormone called GDF15. The hormone is produced by the fetus in the placenta and rises a lot during pregnancy. 

The findings were published this week and come from a team spanning the University of Southern California, the University of Cambridge in the United Kingdom, and Sri Lankan researchers.

At least 7 in 10 pregnant women have nausea and vomiting during pregnancy. About 2 in 100 pregnant women have extreme symptoms known as hyperemesis gravidarum (HG), which can lead to weight loss, dehydration, and hospitalization. The condition increases the risk of other serious pregnancy complications like preeclampsia and preterm birth, and it’s often underdiagnosed.

Among the study’s key findings is that not everyone is equally sensitive to GDF15. People who had low levels of it in their body before they were pregnant were more sensitive during pregnancy. People with very high pre-pregnancy levels due to a genetic blood disorder called beta thalassemia were less sensitive to GDF15 during pregnancy.

The researchers conducted a number of analyses to arrive at their conclusions, including analyzing the level of GDF15 present in pregnant people’s blood, analyzing genetic data, and doing laboratory experiments on mice and human cells. The findings pointed toward two possible ways of addressing GDF15 sensitivity. An experiment in mice suggested that giving increasing exposure to GDF15 before pregnancy could help. Another possibility is to give an antibody treatment that blocks GDF15 or its receptors.

“This study provides strong evidence that one or both of those methods will be effective in preventing or treating HG,” researcher Marlena Fejzo, PhD, a clinical assistant professor of population and public health sciences at the University of Southern California Keck School of Medicine, said in a statement.

Fejzo told The New York Times that she had severe symptoms firsthand, becoming unable to eat or drink without vomiting during her second pregnancy in 1999. Her doctor dismissed her concerns and suggested she was exaggerating. She miscarried at 15 weeks after being hospitalized, the Times reported.