Scientists discover potential treatment for pregnancy sickness

Exposing women to a hormone known as GDF15 could help to reduce feelings of sickness during pregnancy, according to new research.

As many as seven in 10 women are affected by nausea and vomiting during pregnancy, with roughly three in 100 experiencing severe, life-threatening pregnancy sickness. But until now, the cause was entirely unknown.

Now, new research published in Nature has revealed that nausea and vomiting during pregnancy may be caused by the growth/differentiation factor 15 protein (GDF15) which is produced by the foetus.

Scientists say exposing women to this hormone ahead of pregnancy could help to build up resilience and reduce these burdensome symptoms.

What is GDF15?

GDF15 is made at low levels by almost any cell or tissue in the body, and appears to have a role in regulating inflammatory pathways. During pregnancy, GDF15 is made by the placenta and rises very rapidly in the early stages.

To study whether the production of this hormone is linked to pregnancy sickness, scientists and researchers from England, Scotland, the USA and Sri Lanka, used data from a number of studies to analyse hormone levels in pregnant women.

The researchers used a combination of approaches including human genetics, new ways of measuring hormones in pregnant women’s blood, and studies in cells and mice.

Hyperemesis gravidarum associated with lower levels of GDF15

The researchers found that a rare genetic variant that puts women at greater risk of persistent and severe vomiting ‐ known as hyperemesis gravidarum ‐ was associated with lower levels of the hormone in the blood and tissues outside of pregnancy.

They also found evidence that high levels of the hormone are associated with little to no nausea and vomiting, providing hope of a new treatment for women at risk of pregnancy sickness.

The theory was also tested in mice, and the researchers found that when exposed to acute, high levels of GDF15, they showed signs of loss of appetite. But when mice were treated with a long-acting form of GDF15, their appetite remained normal.

Professor Sir Stephen O’Rahilly, who led the study, said: “Most women who become pregnant will experience nausea and sickness at some point, and while this is not pleasant, for some women it can be much worse – they’ll become so sick they require treatment and even hospitalisation. We now know why.

“The baby growing in the womb is producing a hormone at levels the mother is not used to. The more sensitive she is to this hormone, the sicker she will become. Knowing this gives us a clue as to how we might prevent this from happening.

“It also makes us more confident that preventing GDF15 from accessing its highly specific receptor in the mother’s brain will ultimately form the basis for an effective and safe way of treating this disorder.”

‘A step closer’ to treating pregnancy sickness

Although some therapies exist to treat pregnancy sickness and are at least partially effective, widespread ignorance of the disorder compounded by fear of using medication in pregnancy mean that many women with this condition are inadequately treated.

Co-author Dr Marlena Fejzo from the Department of Population and Public Health Sciences at the University of Southern California has first-hand experience of hyperemesis gravidarum.

After becoming severely ill when pregnant, to the point she could “barely move without being sick”, Dr Fejzo sought medical attention, but she said very little was known about her condition.

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