Scarlett Johansson's pregnancy has given the actress' look-a-like stunt doubles a job boost - instead of one, she has three for the new The Avengers movie.

Co-star Chris Evans, who portrays Captain America in the film, admits Johansson's all-action sidekicks look so much like the actress, he often mistakes them for the real deal.

He explains, "You walk by her (and say), 'Hey, Scarlett - oh, weird. You're not Scarlett at all. Sorry'. There are a lot of fake Scarletts around."

And director Joss Whedon insists fans won't be able to tell that his leading lady is pregnant when the film comes out, telling Entertainment Weekly magazine, "She's not going to spend the whole movie carrying groceries. We didn't trim any scenes. We're like, 'We'll make it work'."

The actress, who portrays Black Widow in the Marvel movies, is expecting her first child with fiance Romain Dauriac.