Prince William and Kate Middleton at a BAFTA gala in July 2011. She'll have to give up those cinched waists for a bit. Credit: Mark Large-Pool/Getty Images.

There are so many questions to ask now that the palace has confirmed that Duchess Catherine Middleton is pregnant. For the fashion minded among us, one takes precedent over the rest:

What is she going to wear?

Middleton has dazzled royal-watchers all over the world with her wardrobe, a mix of stately shifts, custom gowns, and mass market fashions virtually anyone can buy, that is, if your local Reiss or Zara doesn't sell out of that fabulous blazer the moment she steps out in it.

All The Details: Kate Middleton's Pregnancy

Jessica Morgan, co-founder of the fashion blog Go Fug Yourself, predicts that Middleton will continue mixing High Street with high fashion.

"I cannot imagine that someone who has been so devoted to mixing high and low and to re-wearing stuff is going to spend tons of money on custom maternity wear," she said. "I think she'll continue as she has prior to her pregnancy."

Maternity retailers may well be breaking out the bubblegum cigars in celebration. When Middleton wore a purple Prabal Gurung dress during her trip to Singapore earlier this year, online retailer MyHabit.com sold out of its stock of the wool and silk number in under an hour, despite the $599 price. The $340 Reiss dress Middleton wore last year to meet President Obama and the first lady sold out online within a day and caused Reiss' site to crash twice.

Kate Middleton in that sell-out Prabal Gurung dress. Credit: Samir Hussein/Getty Images.

PHOTOS: Kate Middleton Through the Years

What brands can expect a bump from Middleton's bump? Potentially, the UK retailers Isabella Oliver, Seraphine, and Asos. U.S. favorite A Pea in the Pod doesn't have a brick and mortar store in Britain, but they do ship internationally, and they gave ABCNews.com a few suggestions for Middleton: a roomy blue blazer, a coral convertible sleeve tunic, and J Brand maternity jeans (Middleton wore J Brand jeans three days in a row during her summer tour of Canada).

"Of course, we would be thrilled to work with her in any way we can," said Chris Daniel, president of Destination Maternity, which owns A Pea in the Pod.

Still, there will likely be occasions - galas, dinners with dignitaries, the usual royal responsibilities - when she'll need to call on her favorite designers for custom gowns. Middleton's favorites include Prabal Gurung, Jenny Packham, and Sarah Burton of Alexander McQueen, who designed her wedding dress. None of them currently offer maternity lines, and they didn't respond to ABCNews.com's requests for comment.

Kate Middleton in teal Jenny Packham, May 2012. Credit: Indigo-Pool/Getty Images.

"For formal events, she may have to call in some favors," Morgan said. "But I can't imagine that people won't be sending her piles and piles of things to wear."

Of course, expectations are high. She has big shoes empire waist dresses to fill.

"We haven't had a royal pregnancy that's going to get this much attention since Princess Diana," said Morgan. "She was wearing all the crazy '80s pregnancy gear, the sailor collars, the big sleeves. This is a good opportunity for Kate to wear some very chic maternity wear that can be really exciting."

Princess Diana two weeks before the birth of Prince William. Credit: Tim Graham/Getty Images.