The Duchess of Cambridge has been admitted to hospital in the early stages of labour with her third child.
Catherine and the Duke of Cambridge travelled to the Lindo Wing at St Mary’s Hospital, Paddington, in central London on Monday morning.
Catherine has been on maternity leave since making a last royal visit to a charity lunch in London on 22 March.
The baby will be fifth in line to the throne and the Queen’s sixth great-grandchild.
The birth will be announced with an email to the press and a celebratory tweet 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.
As with her first two children, Kate is hoping for a natural birth and does not know whether she is having a boy or a girl.
Consultant obstetrician Guy Thorpe-Beeston and consultant gynaecologist Alan Farthing are the two senior royal doctors overseeing the birth.
Both were called in for the arrival of Prince George in 2013 and Princess Charlotte in 2015.
The baby’s title will be HRH Prince or Princess of Cambridge.
Favourite names at the bookmakers include Mary, Alice, Alexandra, Elizabeth and Victoria for a girl and Arthur, Albert, Frederick, James and Philip for a boy.
The duchess’s pregnancy was announced in October.
As with her previous two pregnancies, Catherine, 36, has suffered from hyperemesis gravidarum, or severe morning sickness.
The condition affects about one in every 200 pregnancies and results in severe nausea and vomiting – with one of the main dangers being dehydration.