Kate Middleton and Prince William are expecting their second baby Credit: Karwai Tang/ Getty

Kate Middleton is pregnant again! The Duke and Duchess of Cambridge are expecting their second child together and Prince George will be a big brother, Kensington Palace has told Us Weekly 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 second child," the statement from the Palace reads. "The Queen and members of both families are delighted with the news."

This will be the second child for Prince William, 32, and Duchess Kate, 32, who became parents for the first time in July last year when Prince George was born at St. Mary's Hospital in London on July 22. See adorable pics of Prince George's first year.

But as with her first pregnancy, Duchess Kate is suffering from hyperemesis gravidarum, a very acute morning sickness, which required an in-patient stay at King Edward VII's Hospital during her pregnancy with Prince George.

So far with this pregnancy, however, the Duchess is being treated at home. "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 is being treated by doctors at Kensington Palace," the Palace continued.

A Palace rep adds, "She is at home being looked after by the surgeon gynecologist to the Queen, Alan Farthing, and the surgeon gynecologist to the royal household, Guy Thorpe-Beeston."

According to a source close to the couple, William and Kate found out the pregnancy news “very recently.” The source says Kate is around eight weeks pregnant, and both are “very happy, very excited."

Although the couple weren't planning to announce their news before the 12 week mark, due to the Duchess's morning sickness and subsequent cancellation of her appearance in Oxford today, the couple made the “very difficult” decision to announce early, an aide tells Us.

As Us reported last month, the Cambridges had been hoping to conceive a baby this year.

“William and Kate are keen to expand their family and Norfolk is perfect for that," a source said. "Kate would love to be pregnant by Christmas."

A spokesman for the couple reveals rescheduling Kate’s diary will only be done on a “case by case” basis, when asked about her Invictus games and Malta commitments later this month.

“We will be planning this on a case by case basis, it’s too early to talk about Malta and Invictus," the spokesman said.

Britain’s Prime Minister, David Cameron, was quick to congratulate the Royal couple. “Many congratulations to the Duke and Duchess of Cambridge," he said in a statement. "I’m delighted by the happy news that they are expecting another baby."