The couple will use the special page on the royal family website - www.royal.uk/baby - to keep fans in the loop about any royal baby updates, such as his or her birth.
The site states: "In October 2017, Kensington Palace announced that The Duke and Duchess of Cambridge are expecting their third child. Updates will be posted on this page and on @KensingtonRoyal's Twitter account as they become available."
The webpage for the third royal baby doesn't have many details, seeing as much of the information floating around is speculation. Here's what we (sort of) know so far about the Duchess's third pregnancy.
The Duchess suffered from hyperemesis gravidarum, a form of severe sickness.
She suffered this when she was pregnant with her first two children, too. Due to her condition, the Duchess did not carry out planned engagements earlier on in her pregnancy, including Prince George's first day of school. As her pregnancy has progressed, she has attended more royal events.
She is rumoured to be expecting her third child on St George's Day.
Rumours surfaced about her due date after a royal source said she was expecting her third child "around the 23rd of April". "There's no certainty with due dates of course but the Duchess is working off a date around St George's Day and it would be a lovely patriotic coincidence if he or she were born then," the source told The Sun. "One thing's for certain, if it's a boy he won't be called George."
She is likely to give birth in St Mary's hospital, London.
Prince George and Princess Charlotte were born at the Lindo Wing of St Mary's Hospital in west London. Experts say it is likely that their sibling will also be born there.
There's been a spike in the odds for the royal baby name.
The number of people choosing Alice as the potential name for the third royal baby has increased, Aaccording to Ladbrokes. Alice is twice as popular a choice than any other names for the Duke and Duchess of Cambridge's third child, despite no one knowing whether she's expecting a boy or girl.