Hyperemesis gravidarum

Definition:

The presence of extreme, persistent nausea and vomiting during pregnancy that leads to dehydration.

Causes, incidence, and risk factors:

The cause of nausea and vomiting during pregnancy is believed to be rapidly rising serum levels of HCG (human chorionic gonadotropin) secreted by the fetus. Increased estrogen levels have also been implicated. Extreme nausea and vomiting during pregnancy may indicate multiple pregnancy or hydatidiform mole (abnormal tissue growth, not a true pregnancy).