Prince William and Kate celebrate fourth wedding anniversary as they await royal baby

Depending on what happens today, April 29 could be doubly special for Prince William and Kate.

The Duke and Duchess of Cambridge are celebrating their fourth wedding anniversary on Wednesday, as the royal couple awaits the birth of their second child.

Should the little prince or princess arrive on the 29th, that means he or she would share a birthday with the date William and the former Kate Middleton said "I do" at London's Westminster Abbey as the world watched.

Kate previously said she was due in the second half of April, and at this point it's almost May -- so it's thought the baby could arrive at any moment.

And despite being heavily pregnant, it seems the duchess has no plans to slow down. On Tuesday, she was spotted driving away from Buckingham Palace, where she reportedly took son Prince George for a swimming lesson in the palace pool.

As for their anniversary, a Kensington Palace spokesperson says the couple plans to spend the day "privately" -- though we imagine that could change if the new fourth-in-line to the throne decides to make his or her debut.