LONDON (CBS NEWS) – Kensington Palace announced Monday that Prince William and his wife, the Duchess of Cambridge, are expecting their third child.

The announcement released in a statement said the queen was delighted by the news.

Officials say Prince William’s wife, the former Kate Middleton, is suffering from Hyperemesis Gravidarum, a form of severe morning sickness, and would not carry out her engagements Monday.

William and Kate, who are both 35, already have two children, Prince George and Princess Charlotte. Prince George, now four-years-old, was to start his first day of school on Monday. His sister, Princess Charlotte, turned two in May.

Kate suffered the same severe morning sickness when she carried her first two children, forcing the couple to make their baby news public perhaps earlier than they would have liked due to the necessity to cancel Kate’s public events.

Their choice of school for Prince George, Thomas’s Battersea in south London, indicated that the Cambridges were settling into their Kensington Palace apartment, having moved recently from their home in Norfolk, England, Anmer Hall.

The new baby will bump its Uncle Harry — Prince Harry to the rest of the world — out of the top-five in the royal line of succession.