The Back-up Plan

• Directed by Alan Poul
• Written by Kate Angelo
• Starring Jennifer Lopez and Alex O'Loughlin
• Classification: PG

After a four-year hiatus, and having given birth to twins herself, Jennifer Lopez, who is now 40, makes her return to the movies in The Back-up Plan, a blend of a traditional rom-com and pregnancy comedy. The twist here is that the pregnancy comes first, as J.Lo, playing an unmarried, Manhattan pet-shop owner named Zoe opts for the "back-up plan" of going it alone and getting pregnant through artificial insemination.

Wouldn't you know it? On the very day she gets injected with a shot of sperm, she meets a cute guy, Stan (Australian actor Alex O'Loughlin), when they both dive for the same taxi cab in the rain. Stan's a pushy but personable farmer and cheese-maker who she runs into again at the local market. Love blooms before Zoe discovers she's pregnant with twins and she can't figure out how to break the news to Stan.

Surging with hormones - especially after seeing him shirtless on his tractor - she's more full of lust than candour. Trouble is, Stan is the sensitive sort, having been betrayed by his first wife, a hyper-sexual Swede who left him feeling bitter toward all women (rather than, more logically, just hypersexual Swedes).

Though the premise feels forced, you might hope script-writer Kate Angelo ( Will & Grace) could turn this into some decent comic fodder. Making cheese, after all, sounds like a funny way to make a living. What's more, J.Lo - who has probably done more for curves than anyone since the inventor of differential calculus - fretting about getting a big derrière is almost amusing. Mostly though, The Back-up Plan feels like a movie aimed right at the funny bones of four-year-olds.

At one point, Zoe actually calls her beau a "stupid head." Robert Klein, as Zoe's obstetrician, sense's Stan's discomfort with feminine anatomy by yelling, "Vagina, vagina, vagina, vagina, vagina." There's messy eating, an encounter with "poo-poo." When laughs run dry, the camera cuts to Zoe's disabled Boston terrier, Nuts, who needs a cart to support its back legs. As director Alan Poul ( Six Feet Under) said in a press interview, "He's one of the go-to characters for funny."

Between Zoe and Stan's recurrent spats and reconciliations, there are more than a dozen supporting characters used to cover the lack of any real dramatic conflict. Anthony Anderson appears as a playground dad to tell Stan stories about the horrors and joys of fatherhood. Seventies sitcom stars Linda Lavin (as Zoe's mom) and Tom Bosley (as Zoe's mom's boyfriend) appear in a handful of scenes. Then there are Zoe's two pet-shop employees (Eric Christian Olsen as the slacker dude and Noureen DeWulf as the sarcastic sidekick). Zoe also has an acerbic best friend, Mona (Michaela Watkins), to give romantic advice, and finally, there's Zoe's single-mothers group, a gaggle of preciously New Age-y types who beat drums and chant and talk about having children without a "penis partner."

The mothers' group provides the context for the film's physical comedy set piece, a loud and chaotic home-birthing scene (aired during the Superbowl as a preview for the film), which treats giving birth as slightly more disgusting than a horror-movie exorcism. In the midst of The Back-up Plan's overall fluffiness, there's a recurrent message that pregnant women, with their voracious appetites and cumbersome bodies, are gross and icky.

For a farmer, Stan is unaccountably squeamish around these natural processes, but then one has a sense that O'Loughlin's real job here is to find every opportunity to take his shirt off for viewers to ogle. As for Lopez, this is another of her everyday superwoman roles: Zoe's a former global Internet executive with her own Greenwich Village shop, fashionable clothes and supportive friends, who succeeds in accessorizing her perfect lifestyle with a family.