Prince Harry and his wife Meghan - who married in May - will welcome their first child into the world next spring and are "delighted" to be announcing their happy news.
Kensington Palace said in a statement released on Twitter: "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.
"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."
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. pic.twitter.com/Ut9C0RagLk— Kensington Palace (@KensingtonRoyal) October 15, 2018
The news comes after the couple arrived in Australia on Monday for their first major international tour since getting married.
The news comes a few months after Harry, 33, joked he didn't want a large family.
As the couple greeted fans in Dublin in July, Elaine Adam-Stewart, 43, told Harry: "My husband also has red hair and he gave me five children -- when are you and Meghan going to get going?"
She added: "He laughed and said 'five children? Too many.' "
But the 36-year-old former actress' father Thomas Markle previously revealed his daughter has wanted a baby of her own for a "long time."
He said: "She's wanted children for a long time. When she met Harry and she spoke about how much she loves him... there's got to be a child in the making there soon.
"I couldn't be more proud of those two, I think they'll do a fabulous job. They're great and I love then dearly. I'm very happy to have a new son-in-law."