Maternity brand Séraphine sales have soared by 40% since it was revealed Kate Middleton is a fan of their designs.

After donning one of their dresses on her first Royal outing since the birth of Prince George Alexander Louis of Cambridge, Séraphine saw sales rocket further.

New mother Kate Middleton was photographed arriving at her parents’ home in Bucklebury wearing the £50 ($80) Blossom Knot Front Lavender Dress on Wednesday.

Demand for the dress has been so high that the site has now stated that orders will not be shipped for at least another month.

This isn’t the first time that Kate Middleton has worked her magic on Séraphine’s sales.

Maternity brand Séraphine sales have soared by 40 percent since it was revealed Kate Middleton is a fan of their designs

Sales of one item, the £39 ($60) Brooke dress, quadrupled after Kate Middleton was reported to have taken a fancy to it when she was shopping in Sloane Square, according to founder Cecile Reinaud.

Total sales are up 40% since March, when Kate Middleton was linked with the brand.

Kate Middleton has been a fan of Séraphine throughout her pregnancy, ordering over a dozen designs from the brand; who have two West London boutiques, one of which is conveniently located on Kensington Church Street, near Kensington Palace.

Séraphine has four London outlets and sells through the internet to more than 30 countries.

Cecile Reinaud said: “The Kate effect is worldwide. From China, Russia to South Africa, sales are boosted  due to the fact she chose our brand to dress her royal bump.”

Séraphine reported a turnover of £5.2 million ($8 million) in the year ending March 2013 and Cecile Reinaud expects turnover for 2014 to reach £8 million ($12 million).

Séraphine prides itself on offering unrivalled wardrobe solutions for pregnant women, available in their London boutiques and at selected Peter Jones and John Lewis stores, and online through their international websites.

Created by Cecile Reinaud, Séraphine’s collections hope to exude effortless Parisian chic, and have earned the brand an A-list following including Angelina Jolie, January Jones, Claudia Schiffer, Jessica Alba, Jennifer Garner and Kate Hudson.