Why royal baby isn't making U.S. trip

Britain's Prince George and his parents, Prince William and Duchess Catherine, visit a butterfly exhibition at London's Natural History Museum on July 2. Prince George celebrates his first birthday on Tuesday, July 22.

Prince George walks at the museum on July 2.

George takes his first steps in public as his mother holds his hand June 15 in Cirencester, England.

The royal family leaves an airbase in Australia to head back to the United Kingdom on April 25. They took a three-week tour of Australia and New Zealand. It was the first official trip overseas since George's birth.

Catherine and William react as their son bites a small present at the bilby enclosure of Sydney's Taronga Zoo on April 20. One of the zoo's bilbies was renamed George in honor of the young prince.

Catherine holds George as he meets a bilby -- Australia's version of the Easter bunny -- at Taronga Zoo on April 20.

George shakes hands with Lynne Cosgrove, the wife of Australia's governor-general, on the tarmac of Sydney Airport on April 16.

Catherine and William speak to New Zealand Governor-General Sir Jerry Mateparae and his wife, Janine, before boarding a flight to Australia on April 16.

George plays with toys during a visit to the Government House in Wellington, New Zealand, on April 9.

Catherine and George arrive in Wellington on April 7.

William and Catherine speak to Archbishop of Canterbury Justin Welby after George's christening October 23 in London.

In August, Catherine and William pose with George and their dogs Lupo, right, and Tilly in the garden of Catherine's family home in Bucklebury, England.

The Duke and Duchess of Cambridge depart St. Mary's Hospital in London with newborn George on July 23, 2013. He was born the previous day at 4:24 p.m., and he weighed 8 pounds and 6 ounces.

"It's very special," William said after George's birth. The prince had already changed his son's first diaper, the couple told reporters.

The new parents stand in front of the Lindo Wing of the hospital on July 23, 2013.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

• Britain's Prince William and Catherine arrive in New York City for a whirlwind tour Sunday


• The Duke and Duchess of Cambridge will not be accompanied by their son Prince George


• A source says the program of events in the city "doesn't make it appropriate to bring him"


• Their engagements include visits to a children's craft group in Harlem and and NBA game

(CNN) -- New York may be the "city that never sleeps" but that won't come as a shock to the Duke and Duchess of Cambridge who are still new parents and are expecting another baby in April.

Prince George, now a toddler, would no doubt love the bright lights of the big city but he'll have to wait to see them himself. A source close to the couple tells me the main reason he isn't coming is that the program of events "doesn't make it appropriate to bring him."

This visit certainly feels rocket-propelled compared to the leisurely three-week tour of New Zealand and Australia earlier this year, when George did join his parents.

Kate and William will carry out 10 events in just two days: From a children's craft group in Harlem to a high-octane NBA game in Brooklyn; a moment of reflection at the September 11 Memorial and a glittering charity dinner at the Metropolitan Museum of Modern Art.

The couple will separate at one point so that Prince William can give a speech in Washington. There will also be additional private engagements.

Due date announced for William and Kate

Prince George's eventful first year

Prince George meets his animal namesake

Each event has been carefully orchestrated to promote the couple's own interests or those of the British government. Royals are in the fundraising business and if there's anywhere you can make big money, it's in the Big Apple.

The causes the royal couple support are set to benefit hugely from this trip.

The Duke and Duchess will meet the rich, the famous, the powerful and the vulnerable. No other couple in the world has the power to fill a room like the Cambridges can right now.

Their spokesman tells me: "The Duke and Duchess are looking forward to their visit enormously, especially as neither have visited New York or Washington in any capacity before.

"They fondly remember the incredibly warm welcome they received on their last official visit to the U.S.A. (California in 2011) and are very much looking forward to returning to the States."

That last visit was to sunny Los Angeles at a time when people were still sizzling from the hype around the royal wedding. It was an unquestionable triumph.

This time they will be returning to a bitter East Coast winter but the welcome will no doubt be as warm. It may be reminiscent of Princess Diana's first visit to New York. Poignantly, Diana never came here with her husband Prince Charles. Kate and William are the next generation and very much a couple.

Wherever they go in Manhattan, the royals will be greeted by cameras and big crowds.

America's fascination with this fairytale is unmatched.

Unlike Diana's day, many of the best royal moments come now from cell phones belonging to well-wishers.

No doubt Kate will be asked how she is feeling after her bout of morning sickness with her entourage looking-on to make sure she doesn't overexert herself.