The Back-up Plan gets sitcommy early and often, and just for good measure, throws in old TV favorites Tom Bosley and Linda Lavin in brief roles.

But regardless of their presence, or that of the appealing (and frequently shirtless) Alex O’Loughlin in his first leading-man role, this is a vehicle for Jennifer Lopez, who is front and center and looking flawless at all times.

The first time we see her character, Zoe, she’s at the doctor’s office with her feet in the stirrups being artificially inseminated, wearing false eyelashes and perfect lip gloss. In case we couldn’t possibly imagine what she’s thinking, the script from Kate Angelo (a former sitcom writer) offers this helpful voiceover nugget: “Oh, God, I hope this works. I’ve wanted this for so long.”

Yeah, it’s like that.

Director Alan Poul (who also has a TV background) hits every obvious note, complete with pratfalls, pregnancy cliches and cheesy pop-music cues that signal the characters’ emotions in painfully literal fashion. Of course, Zoe eats chicken and ice cream in bed while reading What to Expect When You’re Expecting. He also cuts away to Zoe’s Boston terrier for cheap reaction shots so frequently, it could be a drinking game — and this comes from someone who’s proud to be the human companion to one of these adorable dogs.

All these devices are in service of a plot that’s pretty thin. After years of looking for the right guy, Zoe is prepared to have a baby on her own, only to meet and fall for the hunky Stan (O’Loughlin) just as she’s discovered she’s pregnant. Their meet-cute couldn’t possibly be cuter: Both hop into the same New York cab in the pouring rain. And Stan couldn’t possibly be more perfect. He’s great-looking, romantic, goofy in a charming way, has just the right amount of roguish facial scruff, and he makes organic cheese at his family’s farm upstate. Organic cheese, people! And somehow, he clearly still finds time to hit the gym.

Since they get together pretty early, the rest of the movie consists of contrived flare-ups that threaten to keep them apart. Will Stan freak out and walk away when he finds out Zoe is expecting? How will he react when he discovers she’s having twins? Will Zoe freak out and walk away from Stan because of her childhood abandonment issues? Will there be a mad dash to the hospital once her water breaks? The answers to these questions are never really in doubt.

The Back-up Plan, a CBS Films release, rated PG-13 for sexual content, some crude material and language. Running time: 104 minutes.