A new story in Star magazine claiming that William's girlfriend of seven years is pregnant is "complete nonsense," a palace spokeswoman tells PEOPLE.
The prince, 27, and Middleton, 28, have recently also had to dodge buzz that a royal wedding may be on the way.
Though the two aren't starting their own family, sources say William is practically already part of Middleton's. During a recent lunch, "William was clearly very close to Kate's father, and every time he spoke to him, William replied, 'Yes, Dad,' " an observer told PEOPLE in April.
Prince William is currently in Africa doing charity work with his brother Prince Harry. The brothers are scheduled to watch England play Algeria in the World Cup in Cape Town on Friday. William will then help host a party to boost England's campaign to host the 2018 games and head back to the U.K. early next week to celebrate his 28th birthday.
With reporting by SIMON PERRY