What Is Hyperemesis Gravidarum?

You could call it ‘royal’ morning sickness

woman suffering from morning sickness

Catherine, Duchess of Cambridge (or more commonly “Duchess Kate”), has been in the news as she struggles with an uncommon, severe type of morning sickness called hyperemesis gravidarum.

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While morning sickness commonly causes nausea and vomiting, hyperemesis gravidarum is much more severe, causing a pregnant woman to become dehydrated and to lose weight.

According to high-risk obstetrician Amy Merlino, MD, “Hyperemesis gravidarum is diagnosed by documenting weight loss. Also, blood and urine tests are used to evaluate a woman’s electrolytes and hydration.”

Causes of severe morning sickness

While the cause is unknown, hyperemesis gravidarum seems to be associated with an increase in a particular hormone during pregnancy called beta HCG (human chorionic gonadotropin).

“This hormone is significantly elevated with multiple gestations (such as twins) and with a rare condition called gestational trophoblastic disease,” Dr. Merlino says.

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Genetics may also be a factor.

“There have been a few studies looking at genetic impact. They have found an increased rate of hyperemesis gravidarum in relatives of those currently affected,” Dr. Merlino says.

Many facets of treatment

Various treatments help women who have this severe form of morning sickness, including:

  • Intravenous (IV) hydration
  • Medication
  • Correction of electrolyte abnormalities
  • Nutritional support

Dr. Merlino says, “Hyperemesis gravidarum requires that patients be hospitalized initially. Often, therapy is continued once the patient is stable enough to go home.”

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She says the condition is typically resolved by about 12 weeks into a pregnancy. 

More information

CBS News Story: Duchess Kate Hospitalized for Hyperemesis Gravidarum: What Is It?

Hyperemesis Gravidarum (Severe Nausea and Vomiting During Pregnancy)

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