A hormone produced by the fetus is believed to be the cause of the nausea and vomiting that many women experience during pregnancy, a major discovery that could pave the way for treatments.
Up to seven in ten pregnancies are affected by nausea and vomiting. In some women — between one and three out of 100 pregnancies — these symptoms can be serious. This is called hyperemesis gravidarum and is the most common cause of hospital admission in women during the first three months of pregnancy.
Kate Middleton, the wife of Prince William, suffered from it in particular during her three pregnancies.
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 caused by a hormone produced by the fetus — a protein known as GDF15.
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.
They showed that the degree of nausea and vomiting a woman experiences during pregnancy 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 effect of this hormone.
Notably, the team 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.
Similarly, women with an inherited blood disorder, 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.
The co-author, DD 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.”