Britain's Prince WiIliam, the Duke of Cambridge, (L) poses for pictures with his wife Catherine, Duchess of Cambridge, as they leave the King Edward VII hospital in central London, on December 6, 2012. Prince William's pregnant wife Catherine left a London hospital on Thursday, four days after she was admitted for treatment for acute morning sickness. AFP PHOTO/Leon Neal        (Photo credit should read LEON NEAL/AFP/Getty Images)