Prince William and his wife Kate formally registered the birth of new son Louis on Tuesday, just over a week after the arrival of the latest member of Britain's royal family.
The visit this summer by the second in line to the throne "is at the request of Her Majesty's government and has been welcomed by the Israeli, Jordanian and Palestinian authorities", the palace said in a statement.
"Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child," Kensington Palace said in a statement.
Four new photographs of Britain's Princess Charlotte playing at her family's country home were released by the royal family on Sunday to mark her first birthday.
Prince Harry will meet people affected by Nepal's earthquake last year and Gurkha soldiers who helped in rescue efforts during a four-day visit to the country next month, his office said.