Researchers have discovered the cause of morning sickness, leading to hopes of a cure for the often debilitating pregnancy symptom.

A study has revealed that a hormone produced by the foetus triggers nausea and vomiting. And it appears women who have naturally low levels of the hormone, called GDF15, may experience more severe morning sickness symptoms. Leading researchers to suggest exposing women to the hormone before pregnancy could help curb morning sickness.

“We now know that women get sick during pregnancy when they are exposed to higher levels of the hormone GDF15 than they are used to,” said Marlena Fejzo, PhD, a clinical assistant professor of population and public health sciences at the Center for Genetic Epidemiology at the Keck School of Medicine and the paper’s first author.

With 80% of women affected by morning sickness during pregnancy, and an additional 2% struck with the more severe form called hyperemesis gravidarum (HG), nausea and vomiting can have huge risks for both mum and baby. And up until now, little was known about the cause of morning sickness.

With the link between GDF15, which is produced by the placenta, and morning sickness, comes the possibility of a cure.

“Knowing this gives us a clue as to how we might prevent this from happening,” said Professor Sir Stephen O’Rahilly, MD, co-director of the Wellcome-Medical Research Council Institute of Metabolic Science at the University of Cambridge, who led the collaboration.

The researchers say that lowering GDF15 is one of the ways to potentially ease morning sickness, with this study indicating it’s likely safe to do so. Or, alternatively, a woman could be exposed to the hormone prior to pregnancy, to prepare them for a surge in the hormone once they’re pregnant.

“This study provides strong evidence that one or both of those methods will be effective in preventing or treating HG,” Dr Fejzo said.

The research team will now test whether ‘priming’ a woman with the hormone prior to pregnancy will reduce nausea and vomiting or prevent HG. They’re also keen to test an additional class of drugs that may help with HG by blocking the hormone from binding its receptor to the brain.

“Hopefully, now that we understand the main cause of HG, we’re a step closer to developing effective treatments to stop other mothers from going through what I, and many other women, have experienced,” she said.