The Duke and Duchess of Cambridge with Prince George and Princess Charlotte, Poland. Source: Kensington Palace Twitter

Prince William and Kate Middleton, the Duke and Duchess of Cambridge, have today confirmed they are expecting their third child.

The newest edition to their growing family will be fifth in line to the British throne.

Kensington Palace released the statement today, noting that the Queen and the royal family are “delighted” with the news of the pregnancy.

The news comes as the Duchess has been forced to cancel her planned official duties today, attending the London children’s hospital, as she is being cared for at Kensington Palace as she is suffering from hyperemesis gravidarum – an extreme form of morning sickness.

The onset of this sickness is not surprising, given the Duchess suffered from the same sickness during her first two pregnancies, as was well documented at the time.

The Duke and Duchess are already parents to Prince George, four, and Princess Charlotte, two. The news has been released ahead of Prince George’s first week at school in London.