Photographers and TV crews from Britain, the United States, Canada, Australia, Japan and China, have been outside St Mary's Hospital in London since July 1 waiting for the couple's first child who, regardless of sex, will be third-in-line to the throne.
Royal officials have remained vague on the due date, only saying mid-July, but there was a noticeable rise in anticipation on Tuesday following remarks by Camilla, the wife of William's father and heir-to-the-throne Prince Charles.
"Hopefully by the end of the week, he or she will be there," Camilla said during an official visit in southwest England. "We are all just waiting by the telephone."
As the days of waiting for the new royal heir have rolled into weeks, rumours have sped around the Internet and via Twitter where an account has been set up for the Royal Foetus and the hashtag GreatKateWait is widely used.
The waiting game has proved a boon for bookmakers offering odds on the date of the birth and for public relations companies pulling royal-related stunts to capture the interest of bored journalists looking to fill the time and publication pages.
One bookmaker sent four oversized toddlers with crowns to Buckingham Palace while US TV station NBC stuck a sweepstake on a wall by the hospital for bets on the arrival date.
On Tuesday, a photo of William and Kate lookalikes pushing a pram in a park splashed the front page of one British newspaper.
The Washington Post has described the child of the popular royal couple who married in April 2011 in front of a global TV audience of two billion as the "world's most famous baby".
"For us it's nice to be at the front seat of any historic moment," Francis D'Souza, a TV anchor and reporter from City News in Toronto, told Reuters.
"Canadians love the royals and ... especially love this couple. They're not old and stodgy and stuffy. Before this we were in Calgary, where people had lost everything in the floods. Here the tears are happiness."
To celebrate the baby's arrival, the city of Toronto has announced plans to light up its CN Tower in pink or blue depending on the sex of the royal baby as has Niagara Falls.
The gender of the baby, who will displace Prince Harry as third to the throne behind grandfather Charles and father William, is said to be unknown as the couple want a surprise.
But bookmakers expect a girl and have made Alexandra the favourite for the baby's name, followed by Charlotte, Diana and Elizabeth. George and James are hotly tipped if it is a boy.
Prince William, a helicopter search-and-rescue pilot, is on standby to join Kate for the birth at the hospital where he was born to the late Princess Diana 31 years ago. The baby will be future heir regardless of sex.
The birth will be announced in the traditional way with an envelope containing the baby's details taken from the hospital to Buckingham Palace, where the news will be posted outside.