First trimester

Morning sickness is a common phenomenon in the first trimester. Up to 85% of all pregnant women are affected. Typically, nausea occurs in the early morning hours, but can extend throughout the day and is often accompanied by vomiting, sensitivity to smells, and changes in appetite.

The main cause is considered to be hormonal changes, in particular the sharp increase in the pregnancy hormone human chorionic gonadotropin (hCG) and estrogen. In recent years, the messenger substance GDF15 (Growth Differentiation Factor 15) has also gained importance. Studies show that GDF15 is released in increased amounts by the placenta during early pregnancy and binds to specific receptors in the brain that are involved in regulating nausea and appetite. High GDF15 levels are associated with more severe morning sickness.

The symptoms usually begin between the 5th and 7th week of pregnancy and subside by the end of the first trimester in most women. Although nausea can be distressing , it is often considered medically to be a normal part of the body's adjustment to pregnancy and is usually temporary.

GDF15 is a messenger substance (protein) produced by the body that plays an important role during pregnancy. Especially in the first trimester, it is produced in increased amounts by the placenta and reaches the brain via the bloodstream.

There, GDF15 acts on a special center that controls appetite, nausea, and vomiting, among other things. Researchers believe that this mechanism explains why many pregnant women suffer from nausea in the first few weeks. The higher the GDF15 level rises, the more severe the symptoms can be.

Interestingly, women who already had higher GDF15 levels before pregnancy often experience less nausea. Their bodies seem to be already "accustomed" to the messenger substance. In others, the brain reacts more sensitively to the sudden increase.

Even though GDF15 is blamed for unpleasant symptoms, it probably serves a useful function. It could help protect the body during the sensitive early stages of pregnancy, for example by warning against potentially harmful foods.

GDF15 is therefore a good example of how many typical pregnancy symptoms are part of complex, natural adaptation processes.