Kate Middleton Dress From Portrait in High Demand

Kate Middleton and Prince William posed in pictures with their new son, Prince George, on Monday, but it is Middleton's dress that captured the attention of fans.

The 31-year-old new mother donned a fuchsia-colored maternity frock from Seraphine that featured short sleeves and a flattering empire-cut waist, reported Us magazine.

Furthermore, the "Jolene" dress offers an ample amount of knotted fabric that flatters the figure while also enabling breastfeeding, as the deep v-neckline "pulls aside," according to the company's website.

As soon as the portraits of the royal family debuted, what is known as the "Kate effect" took place online where the dress almost immediately sold out.

"The Kate effect is huge and we have been enjoying a 400 percent growth in sales since it became public that Kate bought Seraphine dresses back in April 2013," said Cecile Reinaud, president of Seraphine Maternity, according to Hello! Magazine.

Due to its newfound popularity, the coveted dress is on back order until Sept. 16, according to Seraphine's website.

As for the royal family portrait, two photos were released Monday featuring the Duke and Duchess of Cambridge, Prince George, their dog Lupo and Tilly, a Middleton family pet.

Middleton's father Michael took the photos at the Middleton family home in Bucklebury, Berkshire.

Meanwhile, it comes as no surprise that the dress worn by the Duchess of Cambridge in the portrait quickly went on backorder. The British royal has cemented herself as a fashion icon as many of her style choices have been globally replicated.

For example, after millions of people viewed the royal wedding between the Duke and Duchess of Cambridge in April 2011, brides across the world were influenced by Middleton's dress, jewelry and décor.

In the U.S., the Duchess' hand-embroidered veil resulted in a 52 percent increase in American brides choosing to wear veils, according to Brides Magazine.