Kristen Bell at the 2013 CMT Music AwardsChristopher Polk/Getty Images for Wonderwall

Kristen Bell isn't her usual bubbly self in her latest movie, the Liz Garcia-directed dark comedy "The Lifeguard." While a lot of that has to do with the fact that her character, Leigh, is on the cusp of her 30s and kinda depressed, at least a small sliver can be attributed to the fact that Bell was pregnant and tired during filming.

The 33-year-old actress, who gave birth to daughter Lincoln in March, tells Collider she found out she was pregnant while on the Pittsburgh set. "My reality was a bit challenging because I was so tired, but I didn't know why," Bell says. "I was like, 'Well, I have mono. Let's just wrap this movie up, and I'm gonna go to the hospital because I have mono, obviously.' And I didn't. I had pregnancy."

For the movie, she tapped into her irresponsible side to play a 29-year-old woman who's decided to take a break from her own life. Bell's Leigh heads down the rabbit hole of emotional regression and self-pity by quitting her reporter job in NYC and moving back in with her parents in the Connecticut 'burbs, where she becomes a lifeguard.

Considering Leigh wears a "Baywatch"-esque red swimsuit for her poolside gig, having a baby on board presented a bit of a wardrobe challenge for Bell. "When I peed on that stick halfway through the movie, needless to say, the next day that I put the suit on, I was sweating that someone would notice," she admits to Vanity Fair.

The timing of her pregnancy is now something of an inside joke between Bell and her fiance, Dax Shepard. When she signed on for the indie, Bell made it clear to Shepard that she'd have a pretty steamy sex scene with her 19-year-old co-star David Lambert (as part of her pre-midlife crisis, Leigh gets involved with a neighborhood teen).

"[Dax] said, 'You know what, I don't care. I trust you. As long as you don't come back pregnant, I don't care,'" she recalls in her VF interview. "And I came back pregnant, which we always joke about."

Also starring Mamie Gummer and Martin Starr, "The Lifeguard" is now in theaters.

[via Collider, Vanity Fair]
Kristen Bell's Lifeguard Sex Scene

The Lifeguard Movie Poster
The Lifeguard
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A reporter (Kristen Bell) quits her job, returns to her old lifeguard duties, and has an affair with... Read More