05/26/2012 at 01:00 PM EDT
She endured a 14-hour flight from Los Angeles, but you'd never know it when a pregnant Reese Witherspoon
showed up at the Cannes Film Festival
on Saturday in a form-fitting black jersey dress that showed off her bump
Witherspoon, who also wore dangling diamond earrings and sky-high fuchsia stilettos, flew to Cannes with her husband Jim Toth
to promote her new movie, Mud
, which premieres Saturday at the festival.
The actress's presence at Cannes while pregnant was all the more surprising given what a small role she has in Mud
The new film, written and directed by 33-year-old indie darling Jeff Nichols, stars Matthew McConaughey
as a fugitive hiding on an island in the Mississippi River. Two teenage boys discover him and try to reunite him with his true love, played by Witherspoon, as bounty hunters close in on him.
Witherspoon said Saturday at a press conference that she was drawn to the script because it reminded her of her own childhood in Tennessee.
"I grew up with my brother in a creek, riding dirt bikes, dirt fishing, everything you see the boys in the movie doing," she said. "When I read Jeff's script, it felt like home. It's a beautiful story about the place I'm from."
But she hesitated before taking the part because she didn't want to overshadow the rest of the cast or the movie itself.
"I like supporting roles but you have to be careful because [big stars] sometimes pull the focus away from the rest of the movie," she said. "But Jeff assured me it was an ensemble movie – and it was."
Nichols said he "needed" Witherspoon.
"Even if her screen time is limited and, bless her heart, I kept her in a motel room most of the time, she still managed to look good," he said. "I needed someone who, when she showed up, it was like, she's here! She had to be believable and stand out at the same time."
Witherspoon and Toth arrived at the festival Thursday and managed to make it to a dinner for Nicole Kidman
's racy new film The Paperboy.