Britain's Prince William and his wife, Kate Middleton, are expecting their first child, St. James Palace announced Monday.

The 30-year-old duchess of Cambridge, who is in the first stages of her pregnancy, was admitted to London's King Edward VII Hospital on Monday and will remain there for several days.

Her child will be third in line for the throne and will be Queen Elizabeth II's third great-grandchild.

Prince William, the second in line for the crown, married Middleton on April 29, 2011, in London.

"The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall and Prince Harry and members of both families are delighted with the news," the palace said in a statement.

The statement said that the duchess of Cambridge had gone into the hospital to be treated for hyperemesis gravidarum, an acute form of morning sickness.

"As the pregnancy is in its very early stages, Her Royal Highness is expected to stay in hospital for several days and will require a period of rest thereafter," the palace said.

The most recent social event at which the duchess participated was last Friday, when she visited what had been her school for 10 years in Pangbourne, west of London, and even dared to demonstrate her aptitude at field hockey. EFE