“Obvious Child” opens Friday at Sundance Cinemas. R, 1:23, two stars out of four.

I like Jenny Slate a lot. The former “Saturday Night Live” cast member is pretty bold about playing larger-than-life, often spectacularly unlikable characters, such as Jean-Ralphio’s sister on “Parks and Recreation.”

Gillian Robespierre’s “Obvious Child” is a great showcase for Slate’s voice while giving her a more down-to-earth character to play. The banter is often fast and filthy, but still finds room for an underlying sweet tone. But the film’s fearlessness trips itself up when it moves into hot-button territory — abortion — and tries to maintain the same jokey say-anything spirit.

Slate plays Donna, a stand-up comedian who specializes in raunchy, highly personal material; the opening scene of her stand-up act, awash in bodily fuild references, likely serves as a warning to the faint of heart that perhaps this movie isn’t for you. After her boyfriend dumps her for putting too much of their personal lives on stage, she falls into bed with Max (Jake Lacy), an aw-shucks nice guy she meets at the comedy club.

They spend the night, a condom may or may not be involved, and at daybreak Donna intends to go her separate ways from Max. The film’s sexual politics, in which women like sex just as much as men and aren’t obsessed with finding the next Mr. Right, are bracingly real for what’s in many ways a romantic comedy.

Then Donna finds out she’s pregnant.

One assumes that this will go the “Knocked Up” route, that Donna will briefly consider having what Jonah Hill called a “shmashmortion” before deciding to keep the baby, because, well, babies. But no, she’s pretty set on having a shmashmortion, and the only real drama in “Obvious Child” comes with whether she’ll tell Max about it at all.

Points to “Obvious Child” for not taking the easy way out. But there’s a point in the film, as the procedure date looms, when it feels like the screenplay needs to shift into a deeper place somehow. But I think Robespierre and Slate are so committed to their agenda, to make an unabashedly pro-choice film that follows through honestly on at that choice, that they end up not doing much at all, just sort of skating over the implications and the repercussions of Donna’s decision.

They don’t want to make it be the end of Donna’s world, but they don’t really end up exploring how it affects her world at all. So, we get jokes like Donna’s friend (Gaby Hoffmann) telling her before a show that “You’re going to kill it out there tonight,” and Donna responding, “Actually, I have an appointment to do that tomorrow.” Ouch.

I happen to support the film’s agenda, but I don’t support letting that agenda swamp that dramatic (not to mention comedic) possibilities of the film. “Obvious Child” does have one extraordinary scene, set at a real Planned Parenthood clinic, that wordlessly addresses abortion more effectively than pages of dialogue do. But aside from that, the film tiptoes around the issue as much as something like “Knocked Up” did — it just tiptoes around the other side.