This document discusses hyperemesis gravidarum, a severe form of nausea and vomiting that affects 0.3-2.0% of pregnancies. It is characterized by severe, prolonged nausea and vomiting leading to weight loss of over 5% of pre-pregnancy weight. The cause is unknown but may involve high levels of hCG, estrogen and thyroid hormones. Risk factors include previous hyperemesis, obesity, multiples, and being a primigravida. Diagnosis involves assessing dehydration, electrolyte imbalances, and ruling out other causes. Management includes antiemetics, IV hydration, thiamine supplementation, and in severe cases terminating the pregnancy.