The sex of Prince William and his wife Catherine's baby will remain a mystery until its expected arrival in mid-July, with the mother likely to opt for a natural delivery, AFP reports citing British royal sources.
The baby, which will be third in line to the throne, will be born in the same London hospital wing where William himself was born to Prince Charles and princess Diana.
While the monarchy is on Twitter, the birth will be announced to the world in the traditional method -- a notice on an easel in the Buckingham Palace forecourt.
The updates from palace sources are the first confirmed details about the birth, expected within weeks, which is sure to command the same feverish global coverage as William and Kate's wedding in April 2011.
"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," a St James's Palace spokesman said.
William will take the military's standard two-week paternity leave from his role as a Royal Air Force search and rescue pilot, though it is not known how long the duchess will take off royal duties.
The Duke of Cambridge plans to be at his wife's bedside for the birth.
The baby will be born in the private Lindo wing of St Mary's Hospital in Paddington, central London, where William was born in 1982 and his brother Harry in 1984.
William and Kate want the gender of their baby to come as a surprise.
"The duke and duchess do not know the sex of their baby and they've decided not to find out beforehand," a source said.
Kate said on a public engagement in March that she did not know whether she was carrying a boy or a girl.
If the baby is a girl, it could not be overtaken in line to the throne by any future younger brothers, following a change in the succession laws hastily agreed by the 16 Commonwealth realms, which include Britain, Canada, Australia and New Zealand.
The new baby will be a prince or a princess and will enjoy the title of royal highness, following a ruling by Queen Elizabeth.
On Saturday the heavily pregnant duchess made her last public appearance before giving birth, attending the Trooping the Colour military parade celebrating the queen's 87th birthday.
-- Appeal for 'sensitivity, dignity, privacy' --
The St James's Palace spokesman appealed for "sensitivity, dignity and privacy", with the events surrounding Kate's stay in hospital in early December, when her pregnancy was announced, "still strong in our memories".
An Indian-born nurse at London's King Edward VII's Hospital was found hanged several days after putting through a prank call from two Australian radio presenters, which resulted in details of Kate's acute morning sickness being made public.
"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," the spokesman said, while appealing for normal daily activity at St Mary's Hospital to be allowed to continue.
A normal delivery package at the hospital's Lindo wing involving a one-night stay costs £4,965 ($7,775, 5,800 euros).
The rooms have satellite television, wireless Internet, daily newspapers, refreshments and a refrigerator.
The wing also boasts a "comprehensive wine list should you wish to enjoy a glass of champagne and toast your baby's arrival".
In 2006, William visited the hospital's refurbished public neonatal unit, cradling two tiny premature babies.
The birth will be overseen by Dr Alan Farthing, the queen's gynaecologist, and his predecessor Marcus Setchell.
The couple could spend the weeks following the birth at Amner Hall, a large Georgian country house on Queen Elizabeth's private Sandringham estate in Norfolk, eastern England.
Rather than take to Twitter, the couple wanted to retain some of the traditional "theatre" surrounding a royal birth announcement and see that it is "done properly".
A proclamation signed by the doctors will be sped under police escort to Buckingham Palace to inform the royal family, before being displayed in the forecourt.
It will be the same easel used for William's birth, which was announced on a sheet of Buckingham Palace A4 paper with the time of birth, signatures and date filled in by hand.