Women's HealthPending review

Hyperemesis gravidarum

An exaggerated response to rising beta-hCG in early pregnancy drives vomiting so severe and persistent that it causes dehydration, electrolyte disturbance and starvation ketosis, a diagnosis of exclusion that can rapidly become an emergency.

First principles

Hyperemesis is the extreme end of a normal physiological spectrum

Nausea and vomiting of pregnancy is thought to be driven by rapidly rising beta-hCG (and oestrogen) acting on the chemoreceptor trigger zone and gut. Most women experience mild-to-moderate 'morning sickness' that settles by mid-pregnancy. Hyperemesis gravidarum is the same mechanism taken to a severe, intractable extreme, which is exactly why conditions producing very high hCG (multiple pregnancy and molar pregnancy) carry the highest risk.

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Educational content pending clinical review. Not medical advice.