Queen Elizabeth was reported to be “delighted” with the news, according to the Sun. The Duke and Duchess of Cambridge already have two children: Prince George and Princess Charlotte. According to the official statement, morning sickness forced Kate to cancel her schedule.
“Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child,” the statement read. “The Queen and members of both families are delighted with the news.
"As with her previous pregnancies, The Duchess is suffering from Hyperemesis Gravidarum. Her Royal Highness will no longer carry out her planned engagement at the Hornsey Road Children's Centre in London today.”
Hyperemesis gravidarum affects about one in every 200 pregnancies and results in severe nausea and vomiting -- with one of the main dangers being dehydration., the BBC reported.
The expectant child will become the fifth in line to the throne behind Prince Charles, Prince William, Prince George and Princess Charlotte.
If a boy, it will be the first time new rules to remove male primogeniture will be invoked, the BBC reported.
The change -- which stops royal sons taking precedence over their female siblings in the line of succession -- went into effect in March 2015.
The child will be the Queen's sixth great-grandchild.