The Duke and Duchess of Cambridge are expecting their second baby.

The Queen and members of both William and Kate's families are ''delighted'' with the news, Kensington Palace said.

Kate is said to be suffering from acute morning sickness, as she did with her first pregnancy, and is being treated by doctors at Kensington Palace. She is no longer joining her husband on a planned engagement in Oxford today.

Prime Minister David Cameron offered his congratulations to the couple today, saying: ''Many congratulations to the Duke and Duchess of Cambridge. I'm delighted by the happy news that they're expecting another baby.''