Hyperemesis Gravidarum
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Hyperemesis Gravidarum

(Severe Morning Sickness; Persistent Vomiting of Pregnancy; HG)

En Español (Spanish Version)


Hyperemesis gravidarum (HG) is a rare condition characterized by frequent, persistent, and severe vomiting and nausea during pregnancy. As a result, women are often unable to take in a sufficient amount of food and fluids, and thus lose more than 5% of their pre-pregnancy body weight. They become dehydrated, and experience vitamin and mineral deficiencies. Treatment may require hospitalization.

HG is a more severe form of nausea and vomiting of pregnancy (NVP), also called morning sickness . Morning sickness affects anywhere between 50% to 90% of pregnant women. HG is estimated to occur in 0.5% to 2% of pregnancies.


There are many theories about the causes of HG, but none have been confirmed. HG is a complex disease that is likely caused by many factors. Some of these include:

  • Vitamin B deficiency
  • Human chorionic gonadotropin (hyperemesis most severe during period of highest HCG levels)
  • Hyperthyroidism (may be a result of high chorionic gonadotropin levels)
  • Endocrine imbalances (high levels of estrogen)
  • A multiple pregnancy (ie, twins or more)
  • Brain nausea-control-center sensitivity to pregnancy changes

The Brain May Be Cause of Nausea

Brainstem and brain

© 2008 Nucleus Medical Art, Inc.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Some researchers have found that the following factors increase your chance of developing HR. If you have any of these risk factors, tell your doctor:

  • History of HG in previous pregnancies
  • Mother or sister with HG
  • A multiple pregnancy
  • Young maternal age
  • No previous completed pregnancies
  • First-time pregnancy
  • Obesity


The following list of symptoms are general and may be caused by other, less serious health conditions. However, if you experience any one of them, call your physician to discuss your condition. Symptoms may include:

  • Severe and persistent vomiting, beginning 4 to 6 weeks after conception, peaking between 9 to 13 weeks, and usually improving and ending between 14 to 20 weeks
  • Progressive weight loss of greater than 5% of original, pre-pregnancy body weight
  • Dehydration, which may show the following signs:
    • Ketones in urine
    • Increased hematocrit (% of red blood cells in blood)
    • Increased pulse rate
    • Decreased blood pressure
  • Rapid heartbeat ( tachycardia )
  • Excessive salivation (ptyalism)
  • Distinctive breath odor (ketonic odor)


Your doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include the following:

  • Weight measurement—to determine if you have lost weight
  • Blood electrolytes—to identify disturbances in salts and other minerals in the blood due to extreme vomiting
  • Ketones—to determine if you are dehydrated
  • Overall condition—ability to perform daily activities; psychological state of mind


Treating HG symptoms early in pregnancy can make you less sick in the long run and can decrease recovery time. Because HG is caused by many factors that vary between women, it is difficult to find a treatment that works for everyone. Talk with your doctor about the best treatment plan for you. Treatment options include the following:


Frequent small meals, bland or dry foods, high-protein choices.

Anti-nausea Medications

Reducing nausea, and thus allowing eating and drinking, will hasten recovery. Due to the risk of stating that a drug is safe for use during pregnancy, very few pharmaceutical manufacturers will say that their drugs are intended for a pregnancy condition like HG (examples: promethazine or prochlorperazine ). However, physicians often recommend that women with HG take certain anti-nausea medications, balancing the potential benefits and risks. Talk to your doctor about the right medications for you.

A common and safe remedy is to take supplemental vitamin B6 (pyridoxine). The American College of Obstetricians and Gynecologists recommends that first-line treatment of nausea and vomiting of pregnancy should start with pyridoxine with or without doxylamine. Pyridoxine has been found to be effective in significantly reducing severe vomiting.

IV Hydration and Anti-nausea Medications

In urgent visit situations, HG can be managed by giving the woman fluids and vitamins intravenously. This can sometimes be done without hospitalization. Very rarely, some women require IV fluids throughout the entire pregnancy.

Nutrition by Vein

If a woman is unable to tolerate food by mouth, she may need to receive nutrition by vein. This is called parenteral nutrition. A special kind of catheter is placed in a large vein and liquid nutrition is given. This can sometimes be done without hospitalization. Enteral feeding —supplying food through a feeding tube into the intestines—is another option (albeit unpopular).

Termination of Pregnancy

In extreme cases, induced abortion may be considered.


Many of the conditions that lead to HG are not preventable, and it is unknown why some women without those conditions develop HG. You can try to reduce your nausea during pregnancy by:

  • Avoiding smells, foods, or other things that stimulate nausea
  • Eating frequent small meals
  • Not allowing yourself to get too hungry or too full


The American College of Obstetricians and Gynecologists

Dartmouth-Hitchcock Medical Center

Hyperemesis Education and Research Foundation

National Organization for Rare Diseases


The Canadian Women's Health Network

The Society of Obstetricians and Gynaecologists of Canada (SOGC)


ACOG issues guidance on the treatment of morning sickness during pregnancy. American College of Obstetrics and Gynecology website. Available at: http://www.acog.org/from_home/publications/press_releases/nr03-29-04-1.cfm . Accessed August 11, 2005.

Beers MH, Berkow R, eds. The Merck Manual of Diagnosis and Therapy . 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999.

Burrow GN, Duffy TP, eds. Medical Complications During Pregnancy . 5th ed. Philadelphia, PA: WB Saunders Company; 1999.

Cunningham FG, Gilstrap LC, Gant NF, Hauth JC, Leveno KJ, Wenstrom KD, eds. Williams Obstetrics . 21st ed. New York, NY: McGraw-Hill; 2001.

Gabbe SG, Niebyl JR, Simpson JL. Obstetrics: Normal and Problem Pregnancies . 4th ed. United Kingdom: Churchill Livingstone; 2003.

Gastroenterology Clinics of North America . Philadelphia, PA: WB Saunders.

Hyperemesis Education and Research Foundation website. Available at: http://www.helpher.org.

Hyperemesis gravidarum. US National Library of Medicine and the National Institutes of Health website. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/001499.htm . Accessed August 6, 2005.

Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, eds. Harrison’s Principles of Internal Medicine . 16th ed. New York, NY: McGraw-Hill Companies, Inc; 2005.

Mahan LK, Escott-Stump S, eds. Krause’s Food, Nutrition, and Diet Therapy . 10th ed. Philadelphia, PA: WB Saunders Company; 2000.

National Organization for Rare Diseases website. Available at: http://www.rarediseases.org.

Quinlan JD, Hill DA. Nausea and vomiting of pregnancy. Am Fam Physician . 2003;68:121-128. American Family Physician website. Available at: http://www.aafp.org/afp/20030701/121.html . Accessed August 12, 2005.

Sadock BJ, Sadock VA, eds. Kaplan and Sadock’s Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry . 9th ed. Philadelphia, PA: Lippincott, Williams and Wilkins; 2003.

Wise MG, Rundell JR, eds. The American Psychiatric Publishing Textbook of Consultation-Liaison Psychiatry: Psychiatry in the Medically Ill . 2nd ed. Washington, DC: American Psychiatric Publishing, Inc.; 2002.

Last reviewed May 2008 by Ganson Purcell Jr., MD, FACOG, FACPE

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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