The Duchess of Cambridge is planning a natural birth for her baby at the same hospital wing where Diana, Princess of Wales, had Princes William and Harry.
With many women choosing to have a Caesarean section to avoid a strenuous labour, there was some speculation that Kate might have opted for surgery.
But the sources confirmed the Duchess will have a natural delivery at the private Lindo wing of St Mary's Hospital in Paddington and will not join those dubbed "too posh to push".
It had been thought that William and Kate were having a girl after the Duchess appeared to stop herself saying the word daughter during an official engagement in March.
But the royal couple do not know their baby's gender and want it to be a surprise when he or she is born sometime in mid July.
A source said: "The Duke and Duchess do not know the sex of their baby and they've decided not to find out beforehand."
In choosing St Mary's, the royal couple have picked the London hospital where William and his brother Prince Harry were born.
[Revealed: Where the royal baby will be born]
The Duchess will be tended by a top medical team led by the Queen's former gynaecologist Marcus Setchell, who delivered the Countess of Wessex's two children.
He will be assisted by Alan Farthing, the former fiance of murdered TV presenter Jill Dando and the Queen's current gynaecologist.
William is expected to be at his wife's bedside.
The birth will be accompanied by an element of theatre, with a notice informing the nation that a new heir to the throne has been born placed on an easel in the forecourt of Buckingham Palace.
It will be taken from the hospital and given a police escort to speed it through the streets of London to the Queen's official residence.
The ornate easel was used to announce the Duke's birth on June 21 1982 but the notice will not be put in place until the Queen and senior members of the Royal Family have been told of the new addition to their family.
William will take paternity leave from his job as an RAF search and rescue helicopter pilot, thought to be two weeks.
But it is not known how long the Duchess will take off from her royal duties to care for her first child.
Kate could take a number of months off and may not return to her public engagements until the new year.
[Former fiance of murdered TV presenter Jill Dando overseeing Duchess's pregnancy]
The couple could spend the weeks following the birth at Amner Hall, a large property on the Queen's Sandringham estate.
A St James's Palace spokesman appealed for sensitive reporting in light of the death of nurse Jacintha Saldanha, who worked at the King Edward VII's hospital where Kate was treated for severe pregnancy sickness.
Ms Saldanha was found dead in December, three days after she was duped by two Australian DJs into releasing information about Kate's condition.
The spokesman said: "Whilst this is a deeply personal and private moment for the Duke and Duchess, they recognise, of course, that it is also a moment of national celebration.
"We appreciate that there will be mass interest in the Duke and Duchess and their baby over the course of the next few months and many people will want to share in their happiness, most significantly around the time of the birth.
"We simply appeal to all members of the media for the appropriate degree of sensitivity, dignity and privacy in their reporting.
"With the events of King Edward VII's hospital still strong in our memories, we would expect any media covering the Duchess of Cambridge's hospitalisation to ensure that the normal functions of the hospital are not impeded by any media presence."