It’s common for pregnant women to experience some degree of morning sickness, but a smaller subset have severe, potentially debilitating nausea and vomiting — and now a new study has pinpointed the likely source of it.

A research team led by the University of Cambridge in the U.K. found that one specific hormone — GDF15 — is the culprit behind hyperemesis gravidarum, which is a condition that causes intense morning sickness during pregnancy.

The study findings were published in the journal Nature on Dec. 13.

Among 120 pregnant women who participated in the research, the half who experienced nausea and vomiting were found to have "substantially higher" levels of GDF15 than the half who had little or no morning sickness.

"We have securely established, for the first time, using well-validated immunoassays and large sample sizes, that GDF15 levels in maternal blood are significantly higher in women who report vomiting in pregnancy, or have a diagnosis of hyperemesis gravidarum, compared to women who report no or low levels of nausea or vomiting," said study co-author Stephen O’Rahilly, a metabolism researcher at the University of Cambridge.

He shared his thoughts in an email sent to Fox News Digital.

GDF15 is produced primarily by the fetus during early pregnancy. Some women are more sensitive to the hormone, putting them at a higher risk of developing severe morning sickness.

The hope is that this finding will enable more treatment options for women suffering from hyperemesis gravidarum, researchers said.

"We now have a clear view of what may cause this problem and a route for both treatment and prevention," said O’Rahilly.

Women who had higher levels of GDF15 before getting pregnant were significantly less likely to develop severe sickness, the study found — only 5% of them developed the condition compared to 60% of the general population.

With this in mind, one potential remedy would be to administer the hormone to high-risk women before pregnancy to allow them to acclimate to it and prevent severe symptoms.

"Our data tentatively suggest that a doubling of pre-pregnancy GDF15 levels would reduce hyperemesis gravidarum risk by 50%," said O’Rahilly. 

"Metformin, a widely used drug that has been given to people with diabetes for over five years, increases GDF15 levels by two- to three-fold and is widely used in pregnancy in many countries."

What to know about severe morning sickness

Around 70% of women experience typical morning sickness, but only around 0.3% to 2% suffer from hyperemesis gravidarum.

The condition can be debilitating, the study authors wrote, making it difficult for pregnant women to eat, drink and participate in daily activities.

Some signs of hyperemesis gravidarum include vomiting more than three times per day, developing severe dehydration and losing 10 pounds or more, according to the Cleveland Clinic website.

Some women may even require hospitalization to receive hydrating fluids intravenously.

The effects of hyperemesis gravidarum are usually worse during the first trimester and then taper off later in the pregnancy.

While GDF15 was found to increase severe sickness, the study authors noted that other factors may also influence the risk.

"There is considerable overlap between symptomatic and asymptomatic women, so GDF15 levels alone cannot be responsible for determining who is and who is not affected, nor can it be used as a diagnostic test for hyperemesis gravidarum," said O’Rahilly.