LONDON (AP) — While morning sickness in pregnant women is common, the problem the Duchess of Cambridge has been hospitalized with is not.

In a statement Monday, palace officials said she was hospitalized with hyperemesis gravidarum, a potentially dangerous type of morning sickness where vomiting is so severe no food or liquid can be kept down. Palace officials said the duchess was expected to remain hospitalized for several days and would require a period of rest afterward.