Kate Middleton pregnant
The Duchess of Cambridge will be staying in hospital for a few days following acute morning sickness (Reuters)

The Duke and Duchess of Cambridge are expecting their first child, St James's Palace has officially confirmed.

Kate Middleton has been admitted to a central London hospital with hyperemesis gravidarum, or very acute morning sickness, the palace said.

A statement read: "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 Duchess was admitted this afternoon to King Edward VII Hospital in central London with hyperemesis gravidarum.

"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."

Pregnancy rumours have been circulating about Prince William and his wife for some time, with some saying her new hairdo was a signal that she was expecting a child.

The Duke of Cambridge also recently accepted a babygro from a member of the public on a royal visit to Cambridge.

Kate's friend Jessica Hay said last month that the couple would be announcing the pregnancy in December.

In a statement issued by No 10, David Cameron said that they would make "wonderful parents".