September 15, 2016 11:30 AM

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Anne Hathaway just gave birth to her son Jonathan Rosebanks in March. But while filming her new monster movie Colossal, which opened at the Toronto International Film Festival, she was actually pregnant with him — something she had to be extra sensitive about.

“There’s some fight scenes in the movie — some falls,” Hathaway told PEOPLE at TIFF, where she was in attendance to support her new film alongside costar Jason Sudeikis.

“There’s one fall in the movie where I actually did trip, and it was just kind of that thing where I fell on my stomach.

“The reaction in the movie is genuine,” adds the actress, 33, whose husband of almost four years is Adam Shulman. “And the crew, everybody around me, everyone freaked out for a second.”

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The Les Misérables Oscar winner adds that filming the movie while pregnant wasn’t much different than how it would be otherwise, aside from having to be a little more mindful.

“Just respecting certain limitations about, like … ‘I know you want me to hit the bed this hard, but I can’t — you’re gonna have to add a sound effect,’ ” she explains, as an example of some behaviors she had to modify while expecting.

Hathaway admits that being pregnant during a film project definitely had its benefits too, though.

“If anything, it was great because through the emotional scenes, I was just there,” she says.

Jen Juneau

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