The Duchess of Cambridge, wife of Prince William, is expecting her second child and being treated for severe morning sickness, royal officials said Monday.

The couple's Clarence House office said they and their families were "delighted" with the baby news.

The former Kate Middleton was being treated at Kensington Palace for severe morning sickness, Clarence House said.

She was hospitalized for the same condition, hyperemesis gravidarum, during her first pregnancy with Prince George, who was born in July 2013.

The illness means the 32-year-old duchess may need extra hydration, medication and nutrients.

British Prime Minister David Cameron said he was "delighted by the happy news that they're expecting another baby."

The new baby will become fourth in line to the throne, pushing Prince Harry to fifth. Toddler Prince George is third and likely to become Britain's monarch one day.