This document discusses hyperemesis gravidarum (HG), a severe form of nausea and vomiting during pregnancy. HG affects 0.3-3.6% of pregnant women and is one of the leading causes of hospitalization among pregnant women. It is defined as nausea and vomiting during early pregnancy when no other cause is identified. HG is thought to be associated with high levels of the hCG hormone and conditions with higher hCG like multiple pregnancies are associated with more severe HG. HG is diagnosed when a woman experiences severe, prolonged nausea and vomiting leading to weight loss of over 5% and dehydration. Treatment involves rehydration, electrolyte replacement, and antiemetic medications to prevent further complications.