Actress Jenny Slate (left) and Director Gillian Robespierre promote their new movie “Obvious Child.” (Marvin Joseph/The Washington Post)

The comic onstage is telling a fart joke, which wouldn’t seem to signal the beginning of a groundbreaking movie or a starmaking turn for an actor.

But one should never underestimate the relatability of flatulence.

Telling those jokes is Donna Stern, the focal point of the new film “Obvious Child,” and she is played by comedian and actor Jenny Slate, who channels her own fluid storytelling style onstage in crafting her character’s voice.

“She sort of picks up on these little nuances of life and what our bodies do and how she is in her relationship,” says Gillian Robespierre, who wrote and directed the movie, which opens in Washington on Friday.

That’s what Donna’s stand-up is about, and it’s also the territory that “Obvious Child” covers — what bodies do and how relationships work. Specifically, the film is about what one 20-something woman in New York chooses to do when she is faced with an unplanned pregnancy.

She gets an abortion.

In town recently to promote their film, Robespierre and Slate are charming, if a little talked out. The camaraderie between them is easy and evident, as is the fact that their talking points are at the ready. Since this is a movie about abortion, being released into the polarized abortion rights landscape of 2014, that makes sense.

The pair outlines their project as a human story, not one that draws bright lines in a well-trod debate.

“We want to become comfortable with the fact that this is not simple,” Slate says. “It is everyone’s right, male or female, to have a complex experience,” she adds, even when that experience is having an abortion.

Robespierre knows there can be a Hollywood aversion to telling this particular type of story, although, she says, “a lot of great movies have tackled unplanned pregnancy,” including “Dirty Dancing” and “Fast Times at Ridgemont High.”

“Unplanned pregnancy does sometimes end in childbirth or adoption,” she notes, which is the territory — think “Knocked Up” and “Juno” — that Hollywood tends toward.

“We hadn’t seen a feature film talk about it in a way that lifted the stigma and let it be complex and let it be difficult and let it be also safe and actually end with the abortion procedure,” where the main character is “not filled with shame and regret,” Robespierre says of abortion on film.

So that is the movie she made.

One quiet scene toward the end of the film does a lot of work in conveying that message.

It’s in the recovery room at Planned Parenthood, after Donna has had the procedure. A range of women, some young, some bored, one sporting a huge engagement ring, sit quietly in gowns and hospital booties. It’s a moment of “relief and recovery together and not feeling isolated or alone,” Robespierre says.

“The bootie shot,” she calls it.

Slate, next to her on the hotel suite couch, looks briefly confused.

“You said that yesterday and I was like, ‘Why did she say that?’ ” Slate then stage whispers: “I was like, ‘Is my butt out and I don’t know it?’ ”

That’s her biggest fear, she confides.

Which is fair. Slate’s performance is vulnerable and revealing enough, no surprise nudity needed.

That Donna is a comedian — not really as a profession, since it’s unclear how much of an income-generating proposition it is — is a useful movie device. Exposition comes with punch lines.

And it lets Slate, 32, showcase her ease on stage, a voice that somehow makes a naive chirp also sound worldly wise.

Slate, who had a brief stint on “Saturday Night Live” and has guest-starred on “Parks and Recreation” and “The Kroll Show,” says she became a stand-up comedian as a way to get into acting. “It seemed the most active way,” she says. “It seemed like the way I had the most control over how people saw me.”

She honed her voice performing in New York, often with her friend Gabe Liedman, who also appears in the film as a friend of Donna’s. (They replicate the delightful chemistry that is also on display in their “Bestie by Bestie” Web series.) Robespierre saw Slate on a show in New York when she was working on the short film version of “Obvious Child” and knew she’d found her lead.

The stand-up scenes in the movie were written by Robespierre and workshopped by Slate. On the day they shot the opening stand-up scene, Slate says she performed two 30-minute sets back to back. She worked from bullet points, notes Robespierre would call out, and blended it with her own performance style.

In addition to making a stigma-free movie about abortion, Robespierre, 35, also wanted to make one that gives viewers some of the gooey sweetness that people find so satisfying in romantic comedies.

“I would love it to be something people play all the time — on their sick day when they want to snuggle in bed and be comforted by their favorite romantic comedy,” Robespierre says.

And it does have a lot of what a sick-day rom-com viewer might want. A grand gesture. A big reveal. Perfectly timed flowers delivered by Max (Jake Lacy), the onetime and possible future romantic interest who is, in Slate’s description, a “sort of a bro, a handsome-face blond-hair nice-biceps business-school dude” who loves her character’s sense of humor.

The night before Donna is scheduled to have her abortion, she goes onstage, where she is funny, confident and operating on the edge of what it is comfortable to hear people talk about into a microphone. She tells the crowd exactly what is happening in that moment in her life.

If someone had told a story like that at the comedy show in Brooklyn that Slate used to run, how does she think it would have gone over?

She thinks about it for a bit.

“If that person was funny, then it would have gone over well. I think the rules apply. If it’s funny, it’s funny.”

Robespierre mulls this question too.

“If I [watched] Donna perform that bit, or anyone perform something that seems maybe too confessional but then they bring you in because it’s heartfelt and touching, I would probably be crying,” Robespierre says.

Slate agrees:

“Oh, I would be crying, but I would be loving it.”