The onset of the nausea and vomiting in hyperemesis gravidarum is typically before the 20th week of pregnancy. Differential diagnosis
Diagnoses to be ruled out include the following:

Investigations
Common investigations include blood urea nitrogen (BUN) and electrolytes, liver function tests, urinalysis, and thyroid function tests. Hematological investigations include hematocrit levels, which are usually raised in HG. An ultrasound scan may be needed to know gestational status and to exclude molar or partial molar pregnancy. Management
Dry bland food and oral rehydration are first-line treatments. Due to the potential for severe dehydration and other complications, HG is treated as an emergency. If conservative dietary measures fail, more extensive treatment such as the use of antiemetic medications and intravenous rehydration may be required. If oral nutrition is insufficient, intravenous nutritional support may be needed. For women who require hospital admission, thromboembolic stockings or low-molecular-weight heparin may be used as measures to prevent the formation of a blood clot. Intravenous fluids
Intravenous (IV) hydration often includes supplementation of electrolytes as persistent vomiting frequently leads to a deficiency. Likewise, supplementation for lost thiamine (Vitamin B1) must be considered to reduce the risk of Wernickes encephalopathy. A and B vitamins are depleted within two weeks, so extended malnutrition indicates a need for evaluation and supplementation. In addition, electrolyte levels should be monitored and supplemented; of particular concern are sodium and potassium. After IV rehydration is completed, patients typically begin to tolerate frequent small liquid or bland meals. After rehydration, treatment focuses on managing symptoms to allow normal intake of food.
There is no significant difference in the neonatal death rate in infants born to mothers with HG compared to infants born to mothers who do not have HG. Children born to mothers with undertreated HG have a fourfold increase in neurobehavioral diagnoses. Epidemiology
Vomiting is a common condition affecting about 50% of pregnant women, with another 25% having nausea. However, the incidence of HG is only 0.3–1.5%. After preterm labor, hyperemesis gravidarum is the second most common reason for hospital admission during the first half of pregnancy. Factors such as infection with Helicobacter pylori, a rise in thyroid hormone production, low age, low body mass index prior to pregnancy, multiple pregnancies, molar pregnancies, and a history of hyperemesis gravidarum have been associated with the development of HG. History
Thalidomide was prescribed for treatment of HG in Europe until it was recognized that thalidomide is teratogenic and is a cause of phocomelia in neonates. Etymology
Hyperemesis gravidarum is from the Greek hyper-, meaning excessive, and emesis, meaning vomiting, and the Latin gravidarum, the feminine genitive plural form of an adjective, here used as a noun, meaning "pregnant [woman]". Therefore, hyperemesis gravidarum means "excessive vomiting of pregnant women". Notable cases
Author Charlotte Brontë is often thought to have had hyperemesis gravidarum.