Being pregnant is no walk in the park. Many expectant mothers struggle especially in the first few weeks, as seven to eight out of ten women worldwide suffer from nausea and vomiting. Some of them are so strong that they can’t keep a bite down for weeks, sometimes months. A prominent example: Kate Middleton. During all three pregnancies, the British Crown Prince’s wife was dependent on medication to combat nausea and was given fluids via a drip to combat dehydration.

So far, not much has been done to combat this extreme form of pregnancy sickness, also known as hyperemesis gravidarum (HD). This could change now. An international team of researchers claims to have found the cause of HG and offers hope for future treatment options.

Some expectant mothers are particularly affected by pregnancy sickness. This extreme form is called hyperemesis gravidarum. Those affected have to vomit excessively or the vomiting cannot be stopped. HG usually begins in the sixth week of pregnancy and persists for weeks. Improvement often only occurs from the 20th week onwards, and for some even later.

For a long time it was unclear what causes hyperemesis gravidarum. But now an international team of researchers claims to have found the answer. As part of a study, they want to have discovered that a hormone is the culprit. The hormone is called GDF15. It is a so-called growth differentiation hormone, which is produced in low concentrations in many organs. The receptors for GDF15 are located in the area of ​​the brain that is also responsible for nausea and vomiting. During pregnancy, the fetus produces an increased concentration of the hormone in the womb through its own production of GDF15.

The study results suggest that GDF15 levels are a significant factor in nausea during pregnancy. And: The severity of the disease probably depends on the amount of GDF15 that the woman had in her body before pregnancy.”We now know that women suffer from nausea during pregnancy if they are exposed to higher concentrations of the hormone GDF15 than they are are used to it,” says study leader Marlena Fejzo from the University of Southern California.

The results have now been published in the journal “Nature”. There have already been indications that GDF15 could be the cause, but they have not been investigated further.

Pregnant women affected by hyperemesis gravidarum vomit more than five times a day, regardless of whether there is anything in the stomach or not and regardless of the time of day. Eating and drinking becomes torture.

The number of affected pregnant women suffering from hyperemesis gravidarum is estimated at 0.5 to 2 percent. It mainly affects young, slim women who don’t smoke and expectant mothers who are expecting twins.

Because expectant mothers can’t keep anything down, they lose weight, some significantly. A loss of more than five percent of body weight due to hyperemesis gravidarum is not uncommon. Pregnant women also struggle with dehydration.

The consequences include deficiency symptoms, weakness and circulatory problems. With prolonged HG beyond the 20th week of pregnancy, the risk of preeclampsia also increases. HG is the most common cause of women being hospitalized in the first three months of pregnancy.

So far, pregnant women suffering from hyperemesis gravidarum can do little about the symptoms. On the one hand, because many medications cannot be taken during pregnancy, and on the other hand, because the cause of the disease was not known. The latest findings now offer a starting point for the development of corresponding medications. According to the researchers, it would be conceivable to administer the hormone before pregnancy or to use a drug that blocks the effect of GDF15 in the brain.

Sources: Nature, University Hospital Freiburg, German Midwives Magazine, Science, BBC