The Duke and Duchess and Cambridge have announced they are expecting their second child.
The new royal baby will be born fourth in line to the throne.
The announcement comes just two months after Prince George celebrated his first birthday.
Here is the latest reaction from public figures to the news.
Clarence House broke the news in a very modern way, announcing the pregnancy on Twitter:
"The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their second child.
A fuller statement released by Kensington Palace read: "The Queen and members of both families are delighted with the news that Their Royal Highnesses are expecting their second child."
It added: "As with her first pregnancy, The Duchess is suffering from Hyperemesis Gravidarum. Her Royal Highness will no longer accompany The Duke of Cambridge on their planned engagement in Oxford today. The Duchess of Cambridge is being treated by doctors at Kensington Palace."
Prince Harry said the news that the duchess was pregnant was "very exciting". He said she was "pretty poorly" but "doing the best she can."
He added: "I think [Prince] George will be over the moon. I think he will be thrilled having another small younger brother or sister."
Prince Edward said of the news: "It's fantastic."
Earl Spencer, the Duke of Cambridge's uncle, told LBC Radio: "It is just such happy-making news. I have never known a period of news where things have looked so dark and bleak around the world and to have this pop up is just fantastic."
Prime Minister David Cameron tweeted: "Many congratulations to the Duke and Duchess of Cambridge. I'm delighted by the happy news that they're expecting another baby."
Later, he told the House of Commons: "On behalf of the whole country, I'm sure the whole House will want to join me in congratulating them on this fantastic news and wishing them well in the months ahead."
Mike Tindall, husband of Prince William's cousin Zara Phillips, revealed he found out about the pregnancy when it broke on the news.
He told talkSport: "I just sent them a message saying it was nice to hear the news on the radio."
Deputy Prime Minister Nick Clegg said: "It is fantastic news they have a growing family. I wish them, especially the Duchess of Cambridge, all the best."
Labour leader Ed Miliband tweeted: "Fantastic to hear that Prince George will soon be a big brother! Congratulations to the Duke and Duchess of Cambridge on their happy news."
He later said in parliament: "I join with the Prime Minister in congratulating the Duke and Duchess of Cambridge on their happy news.
"I too wish them well in the months ahead."
Scottish First Minister Alex Salmond tweeted: "Congratulations & best wishes to the Earl & Countess of Strathearn [as the couple are known in Scotland]. Wonderful to hear they're expecting their second baby - very happy news!"
UKIP leader Nigel Farage tweeted: "Congratulations to the Duke and Duchess of Cambridge who are expecting their second child. A bit of happy news."
Archbishop Of Canterbury Justin Welby tweeted: "Wonderful news that the Duke & Duchess of Cambridge are expecting second child. Praying for the family, and that morning sickness subsides."
The news spread quickly across the world.
On ABC News's Good Morning America, presenter Bob Woodruff described the announcement as "great news".
The Los Angeles Times reported Prince William and Kate expecting second child.
The New York Times said Prince William and His Wife, Kate, Expecting a 2nd Royal Baby.
The New Zealand Herald ran with Kate pregnant again - treated for severe morning sickness.
The Sydney Morning Herald wrote Kate Middleton and Prince William announce they are expecting second child.
The Times of India said Prince William and wife Kate expecting second baby.