Catherine, 36, and the Duke of Cambridge travelled to the Lindo Wing at St Mary's Hospital, Paddington, in central London, according to Kensington Palace.
The Lindo Wing saw the birth of Prince George in 2013 and Princess Charlotte in 2015. Prince William was also born there.
The Duchess of Cambridge has been on maternity leave since making a last royal visit to a charity lunch in London on March 22, the BBC reported.
The child will be the fifth in line to the throne, behind big sister Charlotte, bumping William's younger brother Prince Harry one place down the line of succession and also Queen Elizabeth's sixth great-grandchild.
The birth will be announced via an email to the press and a celebratory message posted on the Kensington Palace Twitter feed.
There will also be the traditional custom of placing a framed paper proclamation on an ornate gold stand behind the iron railings of Buckingham Palace.
To become King or Queen as the third-born royal child is rare, reports the BBC.
But the third child of George III and Queen Charlotte, William IV, took on the task and ruled from 1830 to 1837.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
This website uses cookies.