From the Official British Monarchy Facebook Page:
And here's an excerpt from the Guardian:
I hope that Prince William & Princess Kate have a boy!!
Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting a baby.
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.
And here's an excerpt from the Guardian:
St James's Palace announced the news after the duchess was admitted to hospital on Monday afternoon with acute morning sickness.
It is understood that the duchess is not yet 12 weeks. But the fact she has been admitted to hospital, and is likely to stay there for several days, forced the palace into making an announcement earlier than it would have liked.
... The baby will be the third in line to the throne, bumping Prince Harry, the baby's uncle, to fourth place.
I hope that Prince William & Princess Kate have a boy!!