Hyperemesis gravidarum (HG) begins between the fourth and sixth week of pregnancy. Symptoms usually improve somewhat by the 15th to 20th week of gestation, although some women continue to have frequent relapses throughout pregnancy. Most affected women have numerous episodes of vomiting throughout the day with few if any symptom-free periods, especially during the first three to four months. This leads to significant and rapid weight loss, dehydration, electrolyte disturbances, and nutritional deficiencies often requiring hospitalization.