Elsewhere the news appeared on the front page of newspaper websites in Argentina, India, Canada, France and South Africa.
German tabloid Bild splashed the news across their web front page with a full width picture banner and speculation as to whether the baby would be a "prince or a princess".
The Toronto Star was one of the few to mention the Duchess being taken to hospital in their headline: "Kate Middleton pregnant, hospitalised for morning sickness".
On Twitter, #royalbaby, #NameALegend and Prince William and Kate Middleton were trending within minutes of the news breaking.
English songwriter Cheryl Cole was not bashful about joining in and her tweet boldly stated "I'm sooooooo excited that we're having a royal baby!"
Even the Prime Minister David Cameron tweeted "I'm delighted by the news that the Duke & Duchess of Cambridge are expecting a baby. They will make wonderful parents."
Under the headline "US Reacts With Joy To Royal Baby News" Associated Press news agency summed up the feeling in America with a story that began - "An heir to the British throne is on the way - and Americans may be as enthralled as the Brits."
Kate was laid low by the rare pregnancy illness hyperemesis gravidarum during much of December and was hospitalised for a number of days.
When she was discharged The Australian newspaper reported the news - and a happy comment from the Prince of Wales under the headline "Kate Released, Prince Charles 'Thrilled By Grandfatherhood"'
The royal bump has been fascinating the world and when it made its first real public appearance - when Kate visited her addiction charity in London in February - the headlines quickly followed.
US Weekly, referring to the Duchess' Caribbean break and still using her maiden name, published the headline - "Kate Middleton Shows Off Growing Baby Bump After Mustique Babymoon".
US Today started its web coverage with "Back from the beach, Duchess Kate visits women addicts."
In April the Sydney Morning Herald highlighted how the pregnancy was really beginning to show when Kate appeared at a Scout Association event, publishing the online headline "Now that's a bump: Kate has a swell time".
The Straits Times from Singapore mentioned the event was held on the Queen's birthday - "Queen Elizabeth turns 87 as Kate shows baby bump".
Interest in the royal birth shows no signs of abating and will generate even more headlines and coverage when the baby is born very soon.
- PAA