"Their Royal Highnesses the Duke and Duchess of Cambridge are very pleased to announce that the Duchess of Cambridge is expecting their second child," the statement read. "The Queen and members of both families are delighted with the news."
The Duchess, however, is also suffering from the same severe morning sickness as she dealt with while pregnant with her 1-year-old son, George.
"As with her first pregnancy, the Duchess is suffering from Hyperemesis Gravidarum. Her Royal Highness will no longer accompany the Duke of Cambridge on their planned engagement in Oxford today. The Duchess is being treated by doctors at Kensington Palace," the statement continued.
David Cameron, Britain's prime minister, congratulated the Duke and Duchess in a statement: "I'm delighted by the happy news that they are expecting another baby."