On Monday morning, parking suspension signs have been put up outside the private maternity ward at St Mary’s Hospital in Paddington, Central London.
Barriers have also been set up on the street outside to accommodate the television crews, journalists and photographers that are expected to gather once she goes into labour.
In October the palace said the baby was due in April, but the precise due date has never been confirmed.
There had been rumours that Kate wanted to give birth to her third child at home.
The Lindo Wing is where she had both Prince George, now four, and Princess Charlotte, who is two years old.
Prince William and Prince Harry were also born there.
It was announced last September that the Duke and Duchess were expecting their third baby.
Like her two previous pregnancies, they had to announce the news before she had reached the 12-week stage because she was suffering from hyperemesis gravidarum, an extreme form of morning sickness.
Kate will be looked after by a similar team of doctors and nurses that helped her through Prince George’s birth in July 2013 and Princess Charlotte’s in May 2015.
Guy Thorpe-Beeston, who holds the role of surgeon gynaecologist to the Royal Household, and Alan Farthing, a consultant gynaecological surgeon, will be present.
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He is also surgeon gynaecologist to the Queen.
Kate carried out her last royal engagement on 22 March at the Olympic Park with her husband, and she was also seen at church in Windsor with the Royal family on Easter Sunday.