The Duke and Duchess of Cambridge are expecting their third child, Kensington Palace has announced.

A spokesperson said: "The Duke and Duchess of Cambridge are very pleased to announced that the Duchess of Cambridge is expecting their third child.

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

The Duchess of Cambridge is suffering from hyperemesis gravidarum which causes severe nausea and vomiting. She suffered from it during her previous pregnancies with Prince George, four, and Princess Charlotte, two.

"Her Royal Highness will no longer carry out her planned engagement at the Hornsey Road Children's Centre in London today," a spokesperson added.

The Christening of Princess Charlotte - in pictures Show all 10 1 /10 The Christening of Princess Charlotte - in pictures The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Britain's Prince William and his wife Catherine, Duchess of Cambridge, walk with their children Prince George and Princess Charlotte after the christening of Princess Charlotte at the Church of St Mary Magdalene on the Sandringham Estate The Christening of Princess Charlotte - in pictures Princess Charlotte's christening The Duke and Duchess of Cambridge walk past the crowds at the Church of St Mary Magdalene on the Sandringham Estate with their son Prince George and daughter Princess Charlotte, after her christening The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge talk to Queen Elizabeth, Prince Phillip, Duke of Cambridge and Camilla, Duchess of Cornwall as they arrive at the Church of St Mary Magdalene on the Sandringham Estate for the Christening of Princess Charlotte of Cambridge in King's Lynn The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Michael Middleton, Carole Middleton and Pippa Middleton leave the Church of St Mary Magdalene on the Sandringham Estate for the Christening of Princess Charlotte of Cambridge in King's Lynn The Christening of Princess Charlotte - in pictures Princess Charlotte's christening The Duchess of Cambridge and Princess Charlotte arrive at the Church of St Mary Magdalene in Sandringham, Norfolk, as Princess Charlotte will be christened in front of the Queen and close family. Chris Jackson/PA Wire The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Prince George of Cambridge looks into the pram carrying his sister Princess Charlotte Chris Jackson, Pool Photo via AP The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Prince George of Cambridge leaves the Church of St Mary Magdalene on the Sandringham Estate for the Christening of Princess Charlotte of Cambridge in King's Lynn The Christening of Princess Charlotte - in pictures Princess Charlotte's christening The Duke and Duchess of Cambridge, their son Prince George and daughter Princess Charlotte in a pram arrive for Charlotte's Christening AP Photo/Matt Dunham, Pool The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Queen Elizabeth II stands with Catherine the Duchess of Cambridge whilst pushing Princess Charlotte in a pram AP Photo/Matt Dunham, Pool The Christening of Princess Charlotte - in pictures Princess Charlotte's christening Princess Charlotte pushed in her Silver Cross pram as she leaves the Church of St Mary Magdalene Chris Jackson/PA Wire

"The Duchess is being cared for at Kensington Palace."

The mother-of-two, who married Prince William in April 2011, recently joked about having another baby while being given a present designed for newborns.

While receiving the cuddly toy at an event for start-up tech companies in July, she turned to the Duke while laughing and said: "We will just have to have more babies."

The announcement comes days before Prince George is due to start school on Thursday. The third in line for the throne will be attending an independent school in Battersea, south London which costs £17 thousand per year.