by EBSCO Medical Review Board
(Severe Morning Sickness; Persistent Vomiting of Pregnancy; HG)


Hyperemesis gravidarum (HG) is severe nausea and vomiting during pregnancy. It is not common.


The cause is not known. There are many thoughts about what may cause it, such as:

The Brain May Be the Cause of Nausea
Brainstem and brain
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Risk Factors

HG is more common in young pregnant women. It is also more common in pregnant women who are Asian or Black.

Other things that may raise the risk are:

  • HG during prior pregnancies
  • Prior molar pregnancy—a growth of abnormal tissue in the womb
  • A mother or sister with HG
  • A multiples pregnancy
  • First-time pregnancy
  • Having certain health problems, such as migraines or motion sickness


Problems may be:

  • Nausea and vomiting in early pregnancy
  • Weight loss
  • Light-headedness and fainting


The doctor will ask about your symptoms and health history. A physical exam will be done. Blood and urine tests may also be done.

Other tests may be:

  • Blood tests
  • Urine tests


The goal of treatment is to manage symptoms to prevent weight loss and dehydration. Choices are:

  • Lifestyle changes, such as eating frequent small meals of bland, dry, high-protein foods
  • Anti-nausea medicine
  • Vitamin B6 to ease nausea


The risk of this problem may be lowered by taking prenatal vitamins for 1 month before becoming pregnant.


The American Congress of Obstetricians and Gynecologists 

HER Foundation 


The Canadian Women's Health Network 

The Society of Obstetricians and Gynaecologists of Canada (SOGC) 


About hyperemesis gravidarum. HER Foundation website. Available at: Accessed November 24, 2020.

American College of Obstetrics and Gynecology. Practice Bulletin 189: nausea and vomiting of pregnancy. Obstet Gynecol 2018 Jan;131(1):e15.

Nausea and vomiting in pregnancy. EBSCO DynaMed website. Available at: Accessed November 24, 2020.

Nausea and vomiting of pregnancy. The American College of Obstetricians and Gynecologists website. Available at: Accessed November 24, 2020.

Revision Information

  • Reviewer: EBSCO Medical Review Board Marcin Chwistek, MD
  • Review Date: 09/2020
  • Update Date: 04/20/2021