Prince William and his wife Kate's second child is due in April, an official statement said on Monday.
"Their Royal Highnesses The Duke and Duchess of Cambridge are delighted to confirm they are expecting a baby in April 2015," said a statement from the couple's official residence, Kensington Palace.
The Palace has yet to confirm whether the couple are expecting a boy or girl. However, the use of the word "baby" in the statement rules out the possibility of Kate expecting twins, as she was rumoured to have been.
"The Duchess of Cambridge continues to be affected by Hyperemisis Gravidarum, but her condition is steadily improving."
Evidence that the duchess is coping with intense morning sickness came with the announcement that both Kate and William will join Queen Elizabeth in welcoming the president of Singapore and his wife to Britain on Tuesday.