Surprise, surprise: That dress Kate Middleton wore in her first official family portrait is officially sold out.

K. Midd maternity staple Seraphine made the $79 fuchsia dress, which designer Cecile Reinaud tells the Daily Mail now has a four week long waiting list.

Obviously, Reinaud is thrilled. "She looks so radiant in our bright fuchsia design, it's a perfect choice to show the world her happiness with her newborn and husband," she told the Daily Mail.

And since the Duchess of Cambridge loves a good signature staple piece, she's already worn this dress in a blossom print while leaving the hospital with Prince George. So it makes sense that the dress has sold out in every colorway with wait lists growing by the day. In fact, sales at Seraphine have increased over a whopping 100 percent for the month of July.

ABC News reports that past Seraphine celebrity clients include A-listers like Angelina Jolie, January Jones, Jessica Alba, Jennifer Garner and Kate Hudson–but it's Kate Middleton who's garnered the most interest.

The Kate Middleton Effect: It's real.

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