Hyperemesis gravidarum: extreme nausea and vomiting during pregnancy

75 to 80% of pregnant women experience nausea and vomiting. In 1-3% of cases, the symptoms are so severe that they can lead to significant weight loss and dehydration in the expectant mother. This condition is called hyperemesis gravidarum.

Also read: What can you do about pregnancy nausea and vomiting?

Symptoms of HG

Symptoms of HG usually occur between 4-6 weeks of pregnancy and can peak between 9-13 weeks. Most women experience some relief between weeks 14-20, although up to 20% of women may require care for hyperemesis for the remainder of their pregnancy.

Signs and symptoms of hyperemesis gravidarum include:

Unlike 'normal' pregnancy sickness, where vomiting does not always occur, HG involves severe vomiting, where you cannot keep any food down at all. The nausea also does not go away around 12 weeks of pregnancy, which is usually the case.

Also read: Is low blood pressure during pregnancy dangerous?

Why do some pregnant women experience nausea?

Whether a pregnant woman experiences nausea depends on her sensitivity to a hormone produced by the fetus: the GDF15 protein.

“We now know that women get sick during pregnancy when they are exposed to higher than normal levels of the hormone GDF15,” said Marlena Fejzo, a researcher at the University of Southern California’s Center for Genetic Epidemiology. She and her team found that the severity of symptoms was directly linked to the amount of hormone a woman was exposed to before pregnancy and to the amount of hormone produced by the fetus.

Also read: Persistent nausea: causes and what to do?

What causes nausea and hyperemesis gravidarum?

The scientists were able to identify a rare mutation in the gene that codes for GDF15 in women suffering from hyperemesis gravidarum. This mutation causes abnormally low levels of the hormone throughout the body before pregnancy. Once pregnant and exposed to the GDF15 protein, these women are therefore at greater risk of hyperemesis gravidarum. Unless the fetus also inherits the low-level GDF15 mutation, in which case there is slightly less chance of developing hyperemesis gravidarum.

Treatment of hyperemesis gravidarum

Women with HG are currently prescribed dietary changes, rest and antacids. In severe cases, the expectant mother is admitted to hospital for fluids and nutrition.

Some women find relief from herbs (ginger or peppermint) or hypnosis, and acupressure can also help. The pressure point for reducing nausea is in the middle of the inner wrist, three finger lengths from the wrist crease and between the two tendons. Find the point and press firmly, one wrist at a time, for three minutes.

But there may be hope for the future, as Marlena Fejzo and her team will now attempt to determine whether exposing women to GDF15 before pregnancy can prime them for high levels of the hormone once they become pregnant, and thus reduce the onset of symptoms of hyperemesis gravidarum. Metformin, a drug prescribed to increase GDF15 levels, could be used in patients with a history of the condition.

Another hope lies in a treatment that would prevent the GDF15 protein from binding to receptors in the brains of patients with hyperemesis gravidarum. Several of these drugs are already in clinical trials for cachexia (a complex metabolic disorder that leads to extreme weight loss) and for cancer patients suffering from nausea and vomiting.

Also read: How do you know if you are pregnant with twins?

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