The child is due in Spring 2019.

"Their Royal Highnesses The Duke and Duchess of Sussex are very pleased to announce that The Duchess of Sussex is expecting a baby in the Spring of 2019," the official Twitter handle of the palace said.

Duchess of Sussex, Meghan Merkle, an American actress, married the Duke of Sussex, Prince Harry in May, earlier this year.

The couple have undertaken a historic Australia tour, beginning on Monday.

"Their Royal Highnesses have appreciated all of the support they have received from people around the world since their wedding in May and are delighted to be able to share this happy news with the public," Kensington Palace announced.

Image: twitter.com/KensingtonRoyal