* Royal couple's baby news met with hysteria, humour
* Expectant duchess spends second day in hospital
* Pregnancy likely to dominate tabloid press in Britain
By Mike Collett-White
LONDON, Dec 4 (Reuters) - At least Britain's Prince William and his wife Catherine have fewer things to worry about now they have announced they are expecting their first child.
A day after breaking the news, the couple popularly known as "Wills and Kate" received advice from the world's media and public on what to call the offspring, what he/she/they will look like, what to wear during pregnancy and even what the child was thinking inside the womb.
In an instant reminder of the goldfish bowl of attention the next generation of royals is destined to live in, newspapers splashed the story across their front pages on Tuesday and filled column after column with news, views and speculation.
"Extinguish all rational thought," the Independent newspaper's commentator John Walsh wrote.
In his article entitled "A feelgood foetus?" he praised the royal family's "impeccable" timing, temporarily diverting attention as it has from Britain's battle with debt and economic stagnation and a blazing row over press regulation.
Tabloid newspapers will relish the chance to cover every twist and turn of the pregnancy and birth, and they have not held back in their opening salvoes.
The Sun, Britain's biggest selling daily newspaper, gave a lengthy account of the announcement concluding with a bizarre photo-montage of what a royal heir might look like created by the Sun's "graphic experts".
Not to be outdone, the royalty-obsessed Daily Mail dedicated its first 13 pages to the topic of the couple, formerly known as the Duke and Duchess of Cambridge, and their baby.
Online it ran an analysis comparing two mock-ups of the yet-to-be-born child. Washington-based Joe Mullins produced celebrity-style "beauty" shots, while the MorphThing website came up with significantly less flattering images.
Bookmakers quickly offered odds on the name of the newborn.
Elizabeth, the name of the reigning queen and William's grandmother, looks a decent bet if it is a girl, as does Diana, after his late mother, while Frances, John, Charles and James are also among the most popular options.
But why stop at names? Odds are available on the date of the child's birth, the identity of godmother and godfather, hair colour, weight and which celebrity magazine will land rights to the first official pictures.
SECOND DAY IN HOSPITAL
Amidst the light-hearted conjecture and celebrity-style gushing, there is the more serious issue of Kate's health.
The 30-year-old, who married William in a fairytale wedding last year watched by two billion people across the globe, stayed for a second day in hospital on Tuesday to receive treatment for acute morning sickness.
The prince, also 30, spent several hours with his wife on Monday and returned to the King Edward VII Hospital in central London on Tuesday. The duchess has cancelled official engagements over the coming days as she recovers.
She has been suffering from Hyperemesis Gravidarum, a severe morning sickness which experts said did not put the baby at any increased risk but was slightly more common in mothers who were expecting twins.
Boy or girl, the first-born will become third in line to the British throne after a decision last year to change the rules of succession so that males no longer have precedence as heir, regardless of age.
Reports speculated that the couple had been forced into announcing the pregnancy early by the illness, and, in a royal first, they did so via Twitter with the understated message: "The Duke and Duchess of Cambridge are expecting a baby."
Twitter quickly exploded in response, including spoof accounts of the views of the queen and the baby itself.
"I may not have bones yet, but I'm already more important than everyone reading this," was the Tweet from @RoyalFetus, which already has nearly 9,000 followers.
The news may help erase the embarrassment this year of the publication of topless photographs of the duchess, taken while she was on holiday in France, in several European publications despite attempts by Buckingham Palace to block them.
It is also likely to further bolster the monarchy's popularity, already riding high from the 2011 wedding and Queen Elizabeth's Diamond Jubilee celebrations in the summer.
World leaders including British Prime Minister David Cameron and U.S. President Barack Obama sent congratulations to the duke and duchess, and foreign media swiftly weighed in.
On the world edition of the New York Times website, the royal baby story appeared well down the front page yet was the most viewed article on Tuesday.
In Italy, makers of the Naples' famous presepe dolls had already turned out a pregnant Kate version of their celebrated figurines, originally made for traditional Nativity scenes but which have evolved into a running commentary on current events.
Italian television gave the announcement heavy coverage, although ordinary people were less enthusiastic.
"You must be lucky to be concerned about this kind of thing," said Rome resident Daniele Nicastro.
"Really, with all the problems we have, of all things you come and ask me about this?"