Kate Middleton visits The National Fishing Heritage Centre on March 5, 2013 in Grimsby, England. Credit: Mark Cuthbert/UK Press via Getty

Kate Middleton's baby bump is growing -- and so is her wardrobe! The Duchess of Cambridge, who is expecting her first child with Prince William in July, was spotted browsing the racks at London's TopShop store for more maternity clothes on Thursday, March 14.

An eyewitness tells Us Weekly that Middleton, 31, was carrying several clothing items around the shop, including a pair of jeans. On her royal shopping trip, the mom-to-be was accompanied by two guards wearing plain clothes. 

Middleton was last seen shopping at the store in early March. During that trip, she purchased Lovestruck's $55 Deirdre dress with an elasticized waist to accommodate her growing baby bump.

"It's so exciting that the Duchess of Cambridge bought one of my designs," Lovestruck designer Erika Shaw told Us. "I think it's great that Kate wears high street brands." 

For more on Middleton's pregnancy -- and what she and Prince William call their baby-to-be -- pick up the new Us Weekly, on stands Friday.