Hyperemesis Gravidarum in Emergency Medicine

Updated: Feb 04, 2021
  • Author: Feras H Khan, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Practice Essentials

Hyperemesis gravidarum is defined as a severe and intractable form of nausea and vomiting in pregnancy. It is a diagnosis of exclusion. Early treatment of nausea and vomiting of pregnancy may prevent progression to hyperemesis gravidarum.

Signs and symptoms

Nausea and vomiting occur in early pregnancy and do not respond to simple measures, such as reassurance and dietary changes. Physical examination findings may include weight loss and dehydration.

See Presentation for more detail.


Laboratory studies

Laboratory testing may include the following:

  • Obtaining electrolyte, blood urea nitrogen and creatinine, and serum ketone levels
  • Measuring urine gravity and ketones
  • Performing liver function tests if hepatitis is a concern
  • Performing a complete blood count and urinalysis to rule out other causes, with particular concern for pyelonephritis
  • Obtaining serum amylase-to-creatinine ratio and/or lipase level if pancreatitis is a concern

Imaging studies

Ultrasonographic evaluation is recommended to detect molar pregnancy or multiple gestations.

See Workup for more detail.


The initial management of hyperemesis gravidarum should be conservative and may include rest, avoidance of sensory triggers, and dietary recommendations. Alternative therapies may include acupressure.

The only drug approved by the US Food and Drug Administration for the treatment of nausea and vomiting in pregnancy is doxylamine/pyridoxine. The following medications have also been used in women with hyperemesis gravidarum:

  • Vitamins, such as pyridoxine
  • Herbal remedies, such as ginger
  • Antiemetics
  • Corticosteroids
  • Antihistamines

See Treatment and Medication for more detail.



Nausea and vomiting are common in pregnancy, occurring in 70-85% of all gravid women. [1, 2]

Hyperemesis gravidarum is a severe and intractable form of nausea and vomiting in pregnancy, affecting 0.8-2.3% of pregnant women. [2, 3] It is a diagnosis of exclusion and may result in weight loss; nutritional deficiencies; and abnormalities in fluids, electrolyte levels, and acid-base balance. The peak incidence is at 8-12 weeks of pregnancy, and symptoms usually resolve by week 20 in all but 10% of patients. Uncomplicated nausea and vomiting of pregnancy is generally associated with a lower rate of miscarriage, but hyperemesis gravidarum may affect the health and well-being of both the pregnant woman and the fetus.



The etiology of nausea and vomiting of pregnancy is unknown. Many have postulated that nausea and vomiting are protective in pregnancy to reduce exposures to potentially teratogenic materials. Some theories hold that elevated human chorionic gonadotropin (hCG) or estradiol levels could be causative, due to correlations in numerous studies between levels and symptoms, but this has not been demonstrated conclusively. Psychological theories of the etiology are falling out of favor, and the American College of Obstetrics and Gynecology warns that attributing vomiting to psychological disorders has likely impeded progress in understanding the true etiology of hyperemesis gravidarum. [4]



The cause of severe nausea and vomiting in pregnancy has not been identified. Hyperemesis may have a genetic component, as sisters and daughters of women with hyperemesis have a higher incidence.

Hyperemesis is also associated with hyperemesis in prior pregnancy, female gestation, multiple gestation, triploidy, trisomy 21, current or prior molar pregnancy, and hydrops fetalis.

Women with history of motion sickness, migraine headaches, psychiatric illness, pregestational diabetes, being underweight pregestation, [5]  hyperthyroidism, pyridoxine deficiency, and gastrointestinal disorders are also at an increased risk. The use of assisted reproductive technology has been associated with hyperemesis. [6]

Some studies have suggested that Helicobacter pylori infection may play a role in hyperemesis, [7]  but the data are inconclusive.

Cigarette smoking and maternal age older than 30 years appear to be protective.



United States statistics

Hyperemesis gravidarum occurs in 0.5-2% of pregnancies, with the variation in incidence arising from different diagnostic criteria and ethnic variations. [8] Studies have found an admission rate of 0.8% for hyperemesis gravidarum [9] and an average of 1.3 hospital admissions per hyperemesis patient, with an average hospital stay of 2.6-4 days.

International statistics

In a study conducted in Finland, the incidence of hyperemesis gravidarum was 1.3%. [6]

Race- and age-related demographics

Hyperemesis patients are more likely to be nonwhite.

Patients younger than 30 years are more likely to experience hyperemesis.



One study has demonstrated that adverse fetal outcomes are mostly limited to poor maternal weight gain. [10]  Women who gained less than 7 kg in pregnancy were more likely to have fetal complications, but those with hyperemesis and greater than 7 kg weight gain had no increased risk. This research indicates that treating hyperemesis gravidarum such that the patient is able to gain weight portends a better prognosis.


With mild-to-moderate vomiting, the patient and the fetus are unlikely to experience any increased morbidity or mortality. Before the advent of intravenous hydration, hyperemesis was a major cause of maternal death. Currently, mortality is exceedingly rare, but maternal morbidities may include Wernicke encephalopathy from vitamin B-1 deficiency, Mallory-Weiss tears, esophageal rupture, pneumothorax, and acute tubular necrosis. Hyperemesis is the second leading cause of hospitalization in pregnancy, second only to preterm labor. Additionally, many women experience significant psychosocial morbidity, occasionally interfering with assumption of the maternal role and rarely leading to termination of the pregnancy.


Complications of vomiting rarely occur; however, Mallory-Weiss tears and esophageal perforations have been reported.

Women with hyperemesis and poor weight gain have lower average birth weights and are more likely to have a small for gestational age infant and may be at higher risk for preterm birth.

In severe cases, without thiamine supplementation, Wernicke encephalopathy may occur (ie, diplopia, nystagmus, disorientation, confusion, coma).

If treatment is unsuccessful, complications of prolonged dehydration and starvation may occur.