It is believed that about 80% of pregnant women experience morning sickness, typically in the form of nausea and vomiting. Some only have mild sickness that goes away after the first two or three months of being pregnant, others might have worse symptoms that last throughout their whole pregnancy. In serious cases, the sickness can be so bad that it causes dehydration, and the expecting mother needs to be hospitalized.
A new research study published in the scientific journal Nature this month titled ‘GDF15 linked to maternal risk of nausea and vomiting during pregnancy’, conducted by an international team of scientists led by Stephen O’Rahilly from the University of Cambridge provides key insights into the causes of morning sickness. The study focuses on a protein and a hormone called GDF15, which enters the bloodstream and affects a part of the brain that usually causes feelings of sickness.
Earlier studies have shown GDF15 to cause nausea and vomiting in pregnant women. In the current work, researchers found that both the baby’s production of GDF15 and the mother’s reaction to it play a big role in causing severe vomiting during pregnancy (known as Hyperemesis Gravidarum or HG for short). They discovered that higher amounts of GDF15 in a mother’s blood are linked to vomiting and HG. Importantly, the study also found that most of the GDF15 in a mother’s blood comes from the developing baby and the placenta.
O’Rahilly believes that in the first three months of pregnancy, the role of GDF15 is to protect the baby. By making the mother feel sick so she avoids eating potentially harmful things it’s possible that the placenta might be sending a signal to the mother to be careful about what she eats. GDF15 is also found in people who are not pregnant, where it might be a signal that tells the brain to avoid harmful substances.
The team looked at the effects of different genetic variations GDF15. They found that women with lower baseline levels of GDF15 while not pregnant had a higher risk of HG. In contrast, women with conditions like beta-thalassemia, which usually have high GDF15 levels, reported very low levels of nausea and vomiting during pregnancy. This observation can be explained by the discovery of the researchers that the body can become less sensitive to GDF15 time. This would also explain why for most women, the morning sickness goes away after the first few months of pregnancy.
The study found that women who had already been exposed to the protein GDF15 before getting pregnant were not as affected by an increase in GDF15 during pregnancy. This was shown in experiments with mice. Mice that were given GDF15 were less affected by a larger amount of GDF15 later, especially in how much they ate.
This is important because it helps us understand why some women have a lot of nausea and vomiting when they are pregnant. The study also offers the possibility that stopping GDF15 from working in pregnant women might be a good way to treat severe morning sickness. It also suggests that increasing GDF15 levels before pregnancy, using treatments like recombinant GDF15 or a drug called metformin, might stop these sicknesses from happening later during pregnancy.
In the future, pregnant women might be given special treatments with antibodies that stop GDF15 or its receptors from working, which could help reduce nausea and vomiting. However, more research is needed to see if these treatments would be safe and effective during pregnancy since we don’t yet fully understand what other roles GDF15 might play in a normal pregnancy.
Anirban Mahapatra is a scientist by training and the author of COVID-19: Separating Fact From Fiction. He is currently finishing up his second popular science book. The views expressed are personal
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