The British royal couple - who are already parents to Prince George, four, and Princess Charlotte, two - have confirmed 35-year-old Catherine's due date following them announcing that she was pregnant again in September.
A statement issued by Kensington Palace said: "The Duke and Duchess of Cambridge are delighted to confirm they are expecting a baby in April 2018."
The new baby will be the fifth in line to the throne, with Prince Harry - the child's uncle - being pushed into sixth.
William, 35, and Catherine - previously known as Kate Middleton - will kick off an exciting year with an official royal tour of Norway and Sweden in early 2018.
Kensington Palace announced: "The Duke and Duchess of Cambridge will undertake an official visit to Norway and Sweden at the request of the FCO in early 2018."
Although Duchess Catherine has once again been suffering from hyperemesis gravidarum - a severe form of morning sickness - she still made a public appearance on Monday (16.10.17) as she danced with Paddington Bear at Paddington Station for a charity event.
After Catherine busted some moves, the couple and Prince Harry, 33, boarded a train where they met with children who are involved with the charities they support, as well as their families.
Whilst in the carriage, a young boy took the opportunity to ask William what Prince George's favorite films and TV shows are and the heir to the throne revealed that 'The Lion King' is very popular at his home.
He said: "He quite likes 'The Lion King', we've watched that a few times, He has watched a few Lego movies as well. Trying to keep him off the television is hard work."