Royal Baby May Give $120 Million Boost to British Economy

— -- The celebratory response to Britain's next baby royal baby may boost the British economy by $120 million, but the economic effects may be stronger if it's a baby princess, according to some experts. It's not hard to notice the unequal sales attention when it comes to the clothing worn by the Duchess of Cambridge, Kate Middleton, compared to that of her husband, Prince William.

Joshua Bamfield, director of the Centre for Retail Research in the England, previously estimated that there was a $400 million economic bonanza that came with the arrival of Prince George in 2013. This time, the boost will likely be around $120 million in retail spending, he said.

"Our view is that any celebrations of 'Baby No. 2' will be low key and we suggest that the boost to retail sales will only be about £80 million sterling, primarily on things like cakes, Prosecco and souvenirs -- mugs, coins and teapots," he told ABC News.

"In the longer term, if the new child is a girl, this will give Britain's retailers and designers a bonanza as royal watchers emulate every new piece of babywear, every new dress, et cetera, and it will go on until she is 25 years old," Bamfield said, noting that through that time the hypothetical princess is "a marked woman indeed."

British maternity clothing maker Seraphine saw an immediate spike in sales when the duchess wore its "pink fuchsia maternity dress." It sold out within hours and the increased Web traffic almost crashed the company website, according to company officials.

"The photo was broadcast worldwide, and since then we've capitalized on the increased international attention by expanding our business –- putting a greater focus on the U.S. market," Cecile Reinaud, founder of Seraphine, told ABC News. The company opened its flagship store in New York last year and has plans to open a second store on Madison Avenue next month.

During her second pregnancy, the duchess has worn other Seraphine maternity clothes, including during the royal couple's visit to New York in December. And Reinaud said she expects her second child to also follow in "The Kate effect."

"Prince George now has his own close following, and I expect his little brother or sister to have the same sort of selling power," Reinaud said. "By choosing accessible High Street brands over expensive designer labels, the Duchess of Cambridge has provided a tangible boost to British retail."

Reinaud said she's proud of the brand's loyal celebrity following among stars such as Zoe Saldana, Jessica Alba, Gwen Stefani, Mila Kunis and Carrie Underwood, among others.

"But none of these stars generate the same level of media attention as the duchess -- she is in a class of her own," Reinaud said.

Like mother, like son, whatever Prince George wears also becomes the next big thing in luxury wear. The "Guards Tank Top" that Prince George was seen wearing in photos released in December is still sold out, said its designer Cath Kidston, though the company hopes to add it again this year.

"Prince George has had such a huge influence on children's fashion, making traditional clothes fashionable, and bringing a spotlight to dressing children like children, and not 'Mini-Me,'" British designer Rachel Riley told ABC News.

When Prince George wore the "Sailboat Smocked Dungarees" made by Riley in his first official engagement in New Zealand, the company's Web traffic spiked in the U.S. and U.K., she said.

Riley has had other royal customers in her twenty years of business, including the queen's grand-daughter wearing dresses at the Boat Parade and Buckingham Palace during the queen's Diamond Jubilee.

"However Prince George has been named the 'World's Most Influential Toddler' so he has definitely brought the media spotlight to our company," she said.

Designers are waiting with bated breath to find out the baby's gender. If the royal baby is a girl, it will be the first time there has been a princess in the U.K. since Princess Anne in the 1950s and Princesses Elizabeth and Margaret in the 1930s.

"As I love vintage prints, and have been collecting these since I was a teenager, I have made sure that we have plenty of options for both baby girl and baby boy, as well as our Heritage Collection," Riley said.

It's not just baby clothing makers that want to be associated with the next royal baby. The wrap that Prince George first appeared in as a newborn is still the hottest seller of the American company that made it.

Brooklyn blanket and accessories maker aden + anais said that the "jungle jam" wrap that was used when the prince first left the hospital is still the company's best performing product nearly two years later, including in the U.S., Japan and Australia. The product sold out that day in the U.K., and once inventory was replenished August, sales were up 223 percent compared to August 2012, the company said.

Raegan Moya-Jones, CEO and co-founder of aden + anais, said that although her products can be found in 63 countries, "Having Prince George wear our blanket was quite an honor and has really solidified our international presence."

Another celebrity moment for aden + anais was when the baby of another power couple was shown wrapped in another of its blankets. That was of course Beyonce and Jay Z. The company calls that moment a "close second" to the boost that Prince George provided.