Hyperemesis gravidarum

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Hyperemesis gravidarum (from Greek hyper and Latin emesis and gravida; meaning “excessive vomiting of pregnant women”) is a severe form of morning sickness, with unrelenting, excessive pregnancy-related nausea and/or vomiting that prevents adequate intake of food and fluids. Hyperemesis is considered a rare complication of pregnancy but, because nausea and vomiting during pregnancy exist on a continuum, there is no clear boundary between common morning sickness and hyperemesis. Estimates of the percentage of pregnant women afflicted range from 0.3% to 2%.

Hyperemesis gravidarum is a complication of pregnancy, defined as severe and persistent nausea and vomiting that can lead to electrolyte imbalances, weight loss and dehydration [1]. It can have negative consequences on the health of the mother and the fetus. This condition generally resolves as the pregnancy progresses, however most cases require treatment [2]. Hospitalizations and severity of complications can be minimized with early treatment [4].

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:

Development of hyperemesis gravidarum is the result from multiple genetic mutations. Hyperemesis gravidarum usually develops during the 2nd trimester of pregnancy.

The pathophysiology of nausea and vomiting during pregnancy is not entirely understood. It is believed to be associated with human chorionic gonadotropin (hCG), a hormone produced by the placenta during pregnancy [5].

The pathophysiology of nausea and vomiting during pregnancy is not entirely understood. It is believed to be associated with [human chorionic gonadotropin (hCG)], a hormone produced by the placenta during pregnancy. ^[1]

According to most studies, it is believed to be multifactorial and related to some genetic, endocrine and gastrointestinal factors.

• Genetic:
  • More commonly associated with female monozygotic twins
  • Higher risk in patients whose mothers had HG
  • Higher risk among patients that had history of HG in their first pregnancy ^[2]

• Endocrine:
  • hCG, estrogen and progesterone are linked to nausea and vomiting in pregnancy ^[2]
  • Patients that experience nausea and vomiting while taking combined oral contraceptive pills are more likely to develop HG in pregnancy. ^[3]

• Human Chorionic Gonadotropin hormone:
  • Peaks at weeks 9-12, which correlates with an increased severity of nausea and vomiting during pregnancy, as well as the symptoms of hyperemesis gravidarum.
  • The concentration of hCG in the blood and urine is found to be higher among patients with worsened symptoms of HG.^{[2] [4]}

• Gastrointestinal:
  • The presence of H pylori in the intestine is found to be commonly associated in women that experience HG. ^[5]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Hyperemesis gravidarum is caused by many conditions such as:

The cause of HG is unknown. The leading theories speculate that it is an adverse reaction to the hormonal changes of pregnancy. In particular, hyperemesis may be due to raised levels of beta HCG (Human chorionic gonadotrophin) as it is more common in multiple pregnancies and in gestational trophoblastic disease.

Additional theories point to high levels of estrogen and progesterone, which may also be to blame for hypersalivation; decreased gastric motility (slowed emptying of the stomach and intestines); immune response to fragments of chorionic villi that enter the maternal bloodstream; or immune response to the “foreign” fetus.

Historically, HG was blamed upon a psychological condition of pregnant women. Medical professionals believed it was a reaction to an unwanted pregnancy or some other emotional or psychological problem. This theory has been disproved, but unfortunately some medical professionals espouse this view and fail to give patients the care they need.

A recent study gives “preliminary evidence” that there may be a genetic component.^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

If inadequately treated, HG can cause renal failure, central pontine myelinolysis, coagulopathy, atrophy, Mallory-Weiss syndrome, hypoglycemia, jaundice, malnutrition, Wernicke’s encephalopathy, pneumomediastinum, rhabdomyolysis, deconditioning, splenic avulsion and vasospasms of cerebral arteries. Depression is a common secondary complication of HG. The serious, and sometimes fatal complications of HG are almost always avoided with aggressive treatment.

No long-term follow-up studies have been conducted on children of hyperemetic women. Children born to hyperemetic women appear to have no greater risk of complications or birth defects than the general population. However, recent research in fetal programming indicates that prolonged stress, dehydration and malnutrition during pregnancy can put the fetus at risk for chronic disease, such as diabetes or heart disease, later in life. This underscores the importance of aggressive treatment of the condition.

• Nausea and vomiting usually peaks between 2 and 12 weeks of pregnancy and goes away by the second half of pregnancy.
• With proper identification of symptoms and careful follow-up, this condition rarely presents serious complications for the infant or mother.

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