Uma Thurman is rumoured to be pregnant after she ordered several maternity-sized dresses from a posh US boutique.

The Kill Bill star, who already has two children with ex-husband Ethan Hawke, got an assistant to buy the clothes from retailer Fred Segal in Santa Monica. A source said the aide ordered half-a-dozen frocks from Tricky Threads.

"They were all two sizes larger than she usually orders," the insider told the New York Daily News. In July, Thurman denied she was pregnant after pictures of the 38-year-old in a bikini on the island of Corsica with her financier fiance Arpad 'Arki' Busson sparked reports she was expecting.

Actress Thurman said recently: "I love and adore being a mother. "(My children) are the greatest gift I've ever been given." A representative for the star was unavailable for comment.