Hyperemesis gravidarum is caused by multiple factors including hormonal, biological, and environmental influences. It usually occurs in the first trimester when beta hCG and other hormone levels are highest. High beta hCG levels are seen in multiple pregnancies and gestational trophoblastic disease which also increase risk. Vomiting leads to dehydration, electrolyte imbalances, and ketosis as fat stores are broken down instead of carbohydrates. Biochemical changes include low sodium, potassium, chloride, high blood urea and uric acid. Organs like the liver, kidneys, heart and brain can show pathological changes as well.