Hyperemesis Gravidarum

(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 unknown. There are many thoughts about what may cause it, such as:

  • Hormonal changes
  • A lack of vitamin B
  • Hyperthyroidism —hCG levels may affect the thyroid
The Brain May Be 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.

Things that may raise your risk are:

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


HG may cause:

  • Nausea and vomiting in early pregnancy
  • Weight loss of more than 5% of your pre-pregnancy weight
  • Lightheadedness and fainting


Your doctor will ask about your symptoms and health history. A physical exam will be done. You may have:

  • Blood tests
  • Urine tests
  • Weight measurement—to determine if you have lost weight


The earlier you get treatment, the faster you can recover. Talk with your doctor about the best plan for you. Here are some ways to treat HG:


Try to eat frequent, small meals of bland, dry, high protein foods

Anti-nausea Medicines

Treating nausea may allow you to eat and drink. This will help you get better faster. There aren’t any medicines that treat HG. But there are ones that can help control symptoms. Talk to your doctor about the risks and benefits of any medicines you take.

Vitamin B6 is a safe way to treat HG. It may be taken with or without doxylamine (an anti-histamine).

IV Hydration

If you have dehydration, lightheadedness, and fainting, you may need IV fluids and vitamins. Rarely, you may need IV fluids throughout your pregnancy.

IV Nutrition

If you can’t take in enough food by mouth, you may need IV nutrition. A special kind of catheter is placed in a large vein. Liquid nutrition is given through it.

Termination of Pregnancy

In rare cases, induced abortion may be done if all other treatments have been tried.


To lower your chance of nausea during pregnancy:

  • Take prenatal vitamins for one month before you get pregnant.
  • If you had nausea and vomiting during a prior pregnancy, talk to your doctor about taking vitamin B6 and doxylamine when you become pregnant.
  • Stay away from smells, foods, or other things that make you nauseated.
  • Eat frequent, small bland meals.
  • Don't allow yourself to get too hungry or too full.

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. HER Foundation website. Available at: http://www.helpher.org/hyperemesis-gravidarum. Updated April 18, 2013. Accessed July 23, 2018.

Acupuncture. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/biomedical-libraries/natural-alternative-treatments. Updated July 27, 2017. Accessed July 23, 2018.

Herrell HE. Nausea and vomiting of pregnancy. Am Fam Physician. 2014;89(12):965-970.

Morning sickness: nausea and vomiting of pregnancy. The American College of Obstetricians and Gynecologists website. Available at: http://www.acog.org/~/media/For%20Patients/faq126.pdf?dmc=1&ts=20130806T1444487894. Updated December 2015. Accessed July 23, 2018.

Nausea and vomiting in pregnancy. EBSCO DynaMed Plus website. Available at:http://www.dynamed.com/topics/dmp~AN~T114643/Nausea-and-vomiting-in-pregnancy. Updated January 4, 2018. Accessed July 23, 2018.

Practice Bulletin No. 153: nausea and vomiting of pregnancy. Obstet Gynecol. 2015;126(3):e12-e24.

Last reviewed May 2018 by EBSCO Medical Review Board Kathleen A. Barry, MD  Last Updated: 7/24/2018