Forget "First comes love, then comes marriage, then comes baby in the baby carriage." Now it's: "First comes sperm, then comes baby, will new b.f. sign on as Daddy? Maybe."

The Back-up Plan, a pleasant and instantly forgettable rom-com starring Jennifer Lopez, is an effect of the new procreative order that inverts the sequence of courtship and kids. Rather than baby as product of loving couple, loving couple is product of baby.

The film from scriptwriter Kate Angelo (Will & Grace) and director Alan Poul (Six Feet Under) has a shiny look and a breezy feel - the breeze being generated by the plot reversals that come at 10-minute intervals.

From the opening scene, an insemination sequence where Zoe (Lopez) looks at her chipped toenails in the stirrups and worries about her pedicure, the film focuses on the frivolous as a way of not engaging the serious.

Like many women of a certain age, Zoe (Lopez, glowing like a jar of honey in the sun) has so had it with sex without procreation that now she's trying procreation without sex. (She mistrusts men because, it is revealed, her father was a bolter.)

Zoe is the proprietor of an upscale Tribeca pet store (and owner of a disabled Boston terrier that gets more screen time than Eddie, the Jack Russell on Frasier).

After leaving her gynecologist, Zoe runs smack into Stan (Australian actor Alex O'Loughlin), a cheese maker, when he jumps in the same cab as she does.

The remainder of this up-and-down film closely tracks Stan's roller-coaster ride to the heights of new love and the sudden, plunging depths of anxiety about insta-fatherhood.

On the minus side: The Back-up Plan is cutesy and formulaic and has the approximate depth of a cookie sheet.

On the plus: Its leads are easy on the eyes, Lopez wears great clothes, and there are a few cheap laughs.

These giggles are prompted by the film's satirical take on a single-mom support group. It is led by an earnest facilitator and populated by earth mothers, yummy mummies, and the type of nurturer who defines her job as nursing her baby at least through high school graduation.

Lopez does not so much give a performance as cheerfully endure multiple wardrobe malfunctions, including bursting the seam of a dress, getting hosed down while wearing a sequined chiffon frock, and having her water break while wearing a bridesmaid's number.

The Back-up Plan requires no heavy lifting, mental or otherwise.