The future king or queen will be born in the private Lindo wing of St Mary's Hospital, Paddington, where the Duke of Cambridge, who was also born there, will be with his wife throughout the delivery expected next month.
St James's Palace has also moved to end speculation over the gender of the baby by insisting the Duke and Duchess do not know the sex of their baby and have chosen not to be told until it is born.
Asked whether the Duchess had opted for an elective Caesarian birth, an option which has led to some mothers being dubbed "too posh to push", palace sources said she intended to give birth naturally.
They also confirmed that the Duke will only take two weeks statutory paternity leave before he returns to flying duties with his RAF Search and Rescue squadron in Wales.
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He works a four days on, four days off shift pattern at RAF Valley on Anglesey, meaning he could be nearly 500 kilometres away when the Duchess goes into labour.
It is understood that the Duchess will not spend any time in Wales between now and the birth, due in mid-July, dividing her time instead between Kensington Palace and her parents' home in Berkshire.
Contingency plans have been put in place with the Royal Berkshire Hospital in Reading in case the Duchess goes into labour unexpectedly early while visiting her parents.
The notice will then be placed on an easel on the forecourt of the Palace for the waiting world to be given its first information about the future king or queen.
Shortly afterwards, the news will be put out on the Palace's official Twitter feed, though aides stressed that no electronic communication would be made until the public had had a chance to see the official notice, as "it's important that this is done with a degree of dignity and with half an eye on the historical significance" of the occasion.