Kate Middleton
Britain's Catherine, Duchess of Cambridge reacts as she attends women's semifinal hockey match between Great Britain and Argentina at Riverbank Arena at London 2012 Olympic GamesReuters

It's confirmed! Kate Middleton is pregnant with her second baby, the palace announced.

Clarence House on its official Twitter handle announced the news of the second royal baby.

"Their Royal Highnesses the Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their second child," a statement read.

"The Queen and members of both families are delighted with the news.

"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 George
Britain's Prince William, his wife Catherine, Duchess of Cambridge and their son Prince George, pose for the official portrait in London.Reuters/Jason Bell

Prime Minister David Cameron tweeted that he is delighted with the news of second royal baby.

"Many congratulations to the Duke and Duchess of Cambridge. I'm delighted by the happy news that they're expecting another baby," he said.

The official announcement came almost a month after Middleton's childhood friend Jessica Hay confirmed the second pregnancy news to Australia's New Idea magazine.

"Kate's inner circle is buzzing with the news that she is expecting," Hay told Australia's New Day, according to The Hollywood Gossip. "I've heard it from several different friends of theirs now and they're saying that they think there's going to be an official announcement in weeks."

Apparently, in 2012 Hay confirmed Middleton's first pregnancy news just weeks before the official announcement.

Meanwhile, the Duchess is suffering from Hyperemesis Gravidarum, a condition that can cause dehydration and weight loss.

When Middleton was pregnant with Prince George in November 2012, she was admitted at the King Edward VII Hospital with acute morning sickness, Hyperemesis Gravidarum.