Scientists Finally Pinpoint Cause of Severe Morning Sickness

A hormone has been identified as causing morning sickness — including its severe form, hyperemesis gravidarum, which affected Kate Middleton and Amy Schumer

Scientists have discovered the cause of nausea and vomiting associated with the first trimester of pregnancy — and have pinpointed a specific hormone as the culprit in the most severe cases.

The study, published in the journal Nature, pinpointed the hormone GDF15, which the University of Cambridge explains is produced by the placenta, but also other tissues when a woman is not pregnant. The hormone was previously linked to causing nausea and emesis (vomiting), according to a study in the National Institute of Health.

Although it’s called “morning sickness,” these bouts of illness can happen any time — and sometimes can develop into hyperemesis gravidarum, a severe form of morning sickness that can result in weight loss, dehydration, and, according to the Mayo Clinic, hospitalization.

This severe form of morning sickness can affect up to 3% of pregnant people, according to the Cleveland Clinic, which adds that the condition causes the pregnancy to be classified as "high-risk."

But because morning sickness is so common, more serious cases are often dismissed, Dr. Marlena Fejzo, a geneticist at the University of Southern California Keck School of Medicine and a co-author of the new study, told The New York Times.

“I’ve been working on this for 20 years and yet there are still reports of women dying from this and women being mistreated,” Dr. Fejzo told the outlet.

And as she told The New York Times, she decided to study the cause of hyperemesis gravidarum after her own bout with the illness, which was so severe it caused her to have a miscarriage.

Related: Pregnant Amber Rose Says She Has Hyperemesis — But the 'Not Fun' Condition Is 'Totally Worth It'

“We confirmed that higher GDF15 levels in maternal blood are associated with vomiting in pregnancy and HG,” the study said, which added that patients suffering from it could perhaps one day take medications that block the hormone’s effects.

Kate Middleton famously struggled with hyperemesis gravidarum during all three of her pregnancies, causing her to cancel planned appearances and at one point, be hospitalized. Comedian Amy Schumer also landed in the hospital with the condition during her second trimester, which is traditionally when morning sickness eases.

However, in spite of the condition’s recent rise in awareness, some say hyperemesis gravidarum  — and morning sickness in general — is dismissed as just something women need to accept as a part of pregnancy.

Related: Kate's Morning Sickness Is 'Acute'

“There is kind of an assumption made by many people that women should just be able to cope with this,” Dr. Rachel Freathy, who is a geneticist at the University of Exeter, told The New York Times.

The discovery of the hormone’s role in morning sickness, she told the outlet, will  help people realize “this is a real thing rather than something in somebody’s head.”

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