LONDON, ENGLAND - DECEMBER 06: The Duchess of Cambridge, Catherine Middleton and Prince William, Duke of Cambridge leave the King Edward VII hospital where she has been treated for hyperemesis gravidarum, extreme morning sickness at King Edward VII Hospital on December 6, 2012 in London, England. (Photo by Fred Duval/Getty Images)
LONDON, ENGLAND - DECEMBER 06: Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge leave the King Edward VII hospital where she has been treated for hyperemesis gravidarum, extreme morning sickness at King Edward VII Hospital on December 6, 2012 in London, England. (Photo by Danny Martindale/WireImage)
LONDON, ENGLAND - DECEMBER 06: Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge leave the King Edward VII hospital where she has been treated for hyperemesis gravidarum, extreme morning sickness at King Edward VII Hospital on December 6, 2012 in London, England. (Photo by Julian Parker/UK Press via Getty Images)
LONDON, UNITED KINGDOM - DECEMBER 06: Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge leave the King Edward VII hospital where she has been treated for hyperemesis gravidarum, extreme morning sickness on December 6, 2012 in London, England. (Photo by Neil Mockford/FilmMagic)
LONDON, ENGLAND - DECEMBER 06: Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge leave the King Edward VII hospital where she has been treated for hyperemesis gravidarum, extreme morning sickness at King Edward VII Hospital on December 6, 2012 in London, England. (Photo by Danny Martindale/WireImage)
