Duke of Cambridge reveals baby's due date?

The Duke of Cambridge may have accidentally revealed that his baby is due early next year after admitting he and Catherine can start celebrating "this week" - seemingly referring to the three-month mark.

The 35-year-old royal was forced to announced that he and his wife Duchess Catherine, 35, are expecting their third child earlier this month after the brunette beauty missed their four-year-old son Prince George's first day of school due to severe morning sickness - something she's suffered with all of her pregnancies.

And it looks like the prince - who also has two-year-old daughter Princess Charlotte with Catherine - has accidentally spilled when the little one is expected to be born as he admitted they can start "celebrating" their baby news properly from later this week.

Although he didn't confirm the duchess is due early next year, people tend not to celebrate their pregnancy until they hit the three-month mark as there is less chance of miscarriage and it's usually when parents are able to see their baby properly on a scan.

After being congratulated by an audience member at the National Mental Health and Policing conference in Oxford, William - according to the Daily Star newspaper - said: "Thank you, it's very good news. There's not much sleep going on at the moment. It was a bit anxious to start with but we can start celebrating this week."

The couple - who got married in 2011 - announced their pregnancy in a statement.

It said: "Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child. The Queen and members of both families are delighted with the news.

"As with her previous two pregnancies, The Duchess is suffering from Hyperemesis Gravidarum. Her Royal Highness will no longer carry out her planned engagement at the Hornsey Road Children's Centre in London today.

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