Starring Tina Fey, Amy Poehler, and Steve Martin. Rated PG.

Baby Mama, which stars Tina Fey as a baby-craving career woman and Amy Poehler as her white-trash rent-a-womb, isn’t the first preggo comedy Hollywood has squeezed out recently. Its siblings, raunchy-sweet Knocked Up and motor-mouthed Juno, dropped first. But besides the fact that this kid delivers kooky-witty kicks, the film also happens to include the joyously funny line: “I think she wants me to rub olive oil on your taint.” That’s automatic entry to the (barely) PG playpen, baby.

Naturally, the mania-to-mother phenomenon makes irresistible comedy fodder. Here, single, angsty Kate (Fey), VP of a Whole Foodsy grocery chain, is told by her gynecologist that he “doesn’t like” her uterus. Since a “one-in-a-million” chance of getting knocked up apparently sucks, Kate finds Chaffee (Sigourney Weaver), the strangely fertile yet surely post-menopausal owner of a fancy surrogacy centre, who hooks her up with gloriously trashy surrogate Angie (Poehler).

Okay, writer-director Michael McCullers (a Saturday Night Live scribe) has “twists” here that a toddler could spot. But this one’s more about the odd-chick chemistry between deadpan-subtle Fey and Poehler, whose manic Angie reminds you of a hopped-up, karaoke-loving chimpanzee. When Angie can’t open the baby-proofed toilet, her crazed-animal look when Kate catches her squatting in the sink is priceless.

Everybody delivers. Steve Martin is nutso funny as Kate’s ponytailed boss, who rewards employees with forehead-to-forehead eye contact; Weaver is smugly perfect; amusing Dax Shepard is Angie’s scheming-moron boyfriend, Carl; and Greg Kinnear is charming as Kate’s fruit-smoothie-entrepreneur beau. Ultimately, silly-sharp dialogue—as when a ditched Carl howls to Angie “I’m gonna bang all your friends. Consider them banged!”—can make you pretty happy.