Hypermesis gravadarum is a severe form of morning sickness that affects approximately 1-2% of pregnant women. This condition causes extreme nausea, vomiting, and dehydration, which can lead to weight loss, electrolyte imbalances, malnutrition and sometimes the loss of the baby.
Over the past few decades researchers have worked to determine the causes, risk factors, and potential treatments. Studies have suggested that hormonal imbalances, genetic factors, and underlying medical conditions may all contribute to the debilitating condition.
This week researchers at the University of Cambridge released a new study shedding light on the science behind the illness. The culprit? A hormone called GDF15, produced by the fetus.
The severity of pregnancy sickness depends on both the amount of GDF15 produced by the fetus and the mother’s exposure to this hormone before becoming pregnant. However, this discovery offers hope for prevention by exposing mothers to GDF15 prior to pregnancy to build up their resilience.
Nausea and vomiting during pregnancy affects up to 70% of women. In a small percentage, between 1 and 3 out of 100 pregnancies, it can be severe enough to threaten the lives of the mother and fetus, requiring hospitalization and intravenous fluid replacement.
While there are some existing therapies to treat pregnancy sickness, many women are not adequately treated due to a lack of awareness and fear of medication use during pregnancy.
Until recently, the cause of pregnancy sickness was unknown. However, the production of GDF15 by the placenta has recently been identified as a potential cause. Now, an international study involving scientists from the University of Cambridge and other research institutions has made significant progress in understanding the role of GDF15 in pregnancy sickness, including severe cases.
The researchers analyzed data from women participating in several studies, including those at Cambridge University Hospitals NHS Foundation Trust and North West Anglia NHS Foundation Trust. They used a combination of approaches, including human genetics, hormone measurements, and studies in cells and mice.
The study found that the amount of nausea and vomiting experienced by pregnant women is directly linked to the levels of GDF15 produced by the placenta and released into their bloodstream, as well as their sensitivity to the hormone’s nauseating effects.
GDF15 is usually produced at low levels outside of pregnancy. Sensitivity to the hormone during pregnancy is influenced by prior exposure to it. Women with low levels of GDF15 have a higher risk of developing severe pregnancy sickness. Conversely, women with a genetic variant associated with hyperemesis gravidarum or the blood disorder beta thalassemia, which leads to high levels of GDF15 before pregnancy, have a reduced risk of nausea and vomiting.
Professor Sir Stephen O’Rahilly, who led the study, stated that understanding the role of GDF15 in pregnancy sickness provides insights into prevention strategies. The researchers believe that preventing GDF15 from accessing its receptor in the mother’s brain could form the basis of an effective and safe treatment.
Initial experiments on mice showed promising results. Mice exposed to high levels of GDF15 exhibited loss of appetite, suggesting nausea. However, when mice were treated with a long-acting form of GDF15, they did not display similar behavior when exposed to acute levels of the hormone. This suggests that building up tolerance to GDF15 prior to pregnancy could be key in preventing sickness.
Dr. Marlena Fejzo, co-author of the study, has personal experience with hyperemesis gravidarum and emphasizes the need for more research on this common yet poorly understood 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.” Dr. Fejzo said.
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