Kate Middleton and Prince William: pregnant with second child - confirmed

Kate Middleton and Prince William have announced they're expecting their second child.

The royal palace revealed the good news on Twitter - see below.

"The Duke and Duchess of Cambridge are very pleased to announce the The Duchess of Cambridge is expecting their second child," came the first message, mid-morning UK time.

"The Queen and members of both families are delighted with the news that Their Royal Highnesses are expecting their second child."

An official statement from Clarence House also stated: "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."

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."

Here are the tweets:

The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their second child
— Clarence House (@ClarenceHouse) September 8, 2014

The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their second child
— BritishMonarchy (@BritishMonarchy) September 8, 2014

It has also been revealed that Kate is already suffering from morning sickness. The statement continues:

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.

The full statement is here.