This is a major discovery that could improve the lives of future mothers by opening the way to treatments. Researchers have found the origin of the nausea and vomiting that a large number of women experience during pregnancy: the cause is in fact a hormone produced by the fetus.
Up to seven out of ten pregnancies are affected by these unpleasant symptoms. In some women – between one and three pregnancies out of 100 – this vomiting can even be serious. This is called “hyperemesis gravidarum” and is the most common cause of hospital admission during the first three months of pregnancy. Kate Middleton, the wife of Prince William, particularly suffered from this.
The GDF15 hormone involved
According to the results of a study, recently published in the journal Natureinvolving scientists from the University of Cambridge and researchers from Scotland, the United States and Sri Lanka, these ailments – serious or not – are therefore due to a hormone produced by the fetus – a protein known as of GDF15.
They showed that the degree of nausea and vomiting a woman experiences is directly related to both the amount of GDF15 produced by the fetal part of the placenta and sent into her bloodstream, and to her sensitivity to the effect of this hormone.
To achieve this result, researchers studied data from women recruited in a certain number of studies and used a combination of approaches: measurements of hormones in the blood of pregnant women, studies on cells and mice, etc.
The more sensitive the woman is to this hormone, the sicker she will be.
The team also discovered that some women have a much higher genetic risk of hyperemesis gravidarum, associated with lower levels of the hormone in the blood and tissues outside of pregnancy. Likewise, women with hereditary blood diseases, beta thalassemia (which allows them to have naturally very high levels of GDF15 before pregnancy) experience little or no nausea or vomiting.
“The baby growing in the womb produces a hormone at levels the mother is not used to. The more sensitive she is to this hormone, the sicker she will be,” summarized Professor Stephen O’Rahilly, co-director of the Wellcome-Medical Research Council Institute of Metabolic Sciences at the University of Cambridge, one of the authors of the study. “Knowing this gives us a clue as to how we might prevent this from happening,” he continued.
Co-author Dr Marlena Fejzo of the University of Southern California, whose team previously identified the genetic association between GDF15 and hyperemesis gravidarum, had suffered from the condition herself: “When I was pregnant, I could barely move without being sick,” she testified. “I hope that now that we understand the cause, we are closer to developing effective treatments.”