Morning sickness in pregnancy or emesis gravidarum

In the early months of pregnancy, emesis gravidarum (morning sickness) may occur, characterized by episodes of nausea and possibly vomiting that are most likely to occur in the morning. 

The cause is unknown, but the high levels of human chorionic gonadotropin (hCG) secreted by the placenta and progesterone secreted by the ovaries have been implicated.

In some women the severity of these symptoms requires hospitalization for intravenous feeding, and the condition is then known as hyperemesis gravidarum.