hyperemesis gravidarum

Last reviewed 07/2021

Vomiting is a normal feature of early pregnancy, especially between 7 and 12 weeks.

Severe vomiting may cause weight loss and electrolyte imbalance. In very rare instances jaundice may result - thought to be due to severe protein and vitamin malnutrition.

The cause of the vomiting is primarily physiological but psychological factors may affect the apparent severity.

Symptoms correlate with raised levels of Beta Human chorionic gonadotrophin (BHCG).

High levels of BHCG occur in:

  • hydatidiform mole
  • multiple pregnancy

Note that thyroid function should be assessed in all women with hyperemesis gravidarum. This is because hyperthyroidism may result from higher serum concentrations of BHCG, which has TSH-like activity. Generally, hyperthyroidism associated with increased levels of BHCG resolves spontaneously after the first trimester (1).


  1. Prescriber (2002), 13 (10), 50-68.