Surprise! Princess of Wales, Kate Middleton, is back to work in Windsor.

Rumors are swirling that she's expecting her fourth child.

Prince William and Kate have shared the exciting news with King Charles.

Even the late Queen Elizabeth knew about the pregnancy.

Kate took some time off to be with her family but is now back to her royal duties.

Her most recent duty was on May 6.

She warmly welcomed the Chief Executive of the Royal Foundation at Windsor Castle.

Kate and Prince William already have three children together: Prince George, Princess Charlotte, and Prince Louis.

Notably, Kate is a patron of the Royal Foundation of the Prince and Princess of Wales.