Prince William and Kate Middleton are breaking this 58-year-old royal tradition with baby No. 3

The Duke and Duchess of Cambridge have a modern royal family on their hands. Prince William and Kate Middleton have broken royal tradition and have become the first royal couple – in the Queen's immediately family – in 58 years to announce that they are expecting their third child.

Queen Elizabeth herself has four children – Prince Charles, Princess Anne, Prince Andrew and Prince Edward. She announced she was expecting her third child 58 years ago in 1959 when she was pregnant with Prince Andrew. Her Majesty even went on to have a fourth child, Edward, in 1964. Charles, Anne, Andrew and Edward all kept with the tradition of having two children each.

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><img alt=VIEW GALLERY The Queen and Prince Philip have four children Photo: Getty Images

Charles is a father to Prince William and Prince Harry, Anne is a mother to Peter Phillips and Zara Tindall, while Andrew has two daughters, Princess Beatrice and Princess Eugenie, and Edward has a son, James, Viscount Severn and a daughter, Lady Louise Windsor.

Prince William and Kate seemed to be following the same "an heir and a spare" tradition, by welcoming Prince George and Princess Charlotte, but the modern royals have broken the long-standing family rule. They are due to welcome their third child next spring, with Kensington Palace announcing on Monday: "The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child. The Queen and members of both families are delighted with the news."

><img alt=VIEW GALLERY William and Kate are adding to their brood Photo: Karwai Tang/WireImage

While the Queen's children have welcomed two kids each, it's worth noting that members of her extended family have had more than two children. King George V's son the Duke of Kent, who passed away in 1942, had three children – Prince Edward, Princess Alexandra and Prince Michael of Kent. Prince Edward then went on to also have three children – George Windsor (Lady Amelia's father), Lady Helen and Lord Nicholas.

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