During routine scans William and Kate did not ask if they would be welcoming a son or daughter - opting to be surprised as with the duchess's previous pregnancies.
The couple are said to be hugely grateful for the warm wishes they have received from UK fans and those across the globe since Kate's pregnancy announcement last year.
There was speculation that Kate might opt for a home birth, but when she goes into labour she will again be cared for in the private Lindo Wing of St Mary's Hospital, where Prince George and Princess Charlotte were born.
And just like her previous pregnancies, she is likely to have a team of more than 20 top medical experts and other staff working or on stand-by from Imperial College Healthcare NHS Trust, which runs St Mary's.
Consultant obstetrician Guy Thorpe-Beeston and consultant gynaecologist Alan Farthing will be among the team, two senior medics who were involved in helping to deliver Kate's previous children.
Mr Farthing, the Queen's surgeon gynaecologist, was engaged to BBC presenter Jill Dando when she was shot dead in April 1999. He was a pioneer in keyhole surgery and today specialises in using the technique to treat gynaecological cancer patients.
Mr Thorpe-Beeston, surgeon-gynaecologist to the Royal Household, delivered Charlotte in 2015.
Kate's baby is expected in April and, although a due date has not been released, it is thought the infant will be born in the second half of the month.
Preparations for the media coverage of the birth begin in earnest on Monday, with crowd barriers going up in the street opposite the Lindo Wing in Paddington, central London, and parking restrictions coming into force in the area.
Bookies believe Kate will have a girl and a large number of punters have placed bets on the baby being named Mary, the favourite with firms like William Hill and Coral.
Once news of the birth has been announced on the official Kensington Palace Twitter and Instagram accounts, a bulletin notice declaring the birth will go on display on an easel in the forecourt of Buckingham Palace.
Kate is likely to take an extended period off to recover and nurse the latest addition to her family but is expected to attend Prince Harry and Meghan Markle's wedding on May 19.
As a mother of three children under the age of four, the duchess's role as a parent is likely to be her focus for the next few years, providing a loving and stable home for her family.