Womb Mates

"Baby Mama" isn't exactly laugh-out-loud funny. It's more quiet-chuckle funny, which is fine, too. This latest addition to the pregnancy comedy trend, starring Tina Fey as an overachieving corporate vice president who hires a working-class party girl (Amy Poehler) to be a surrogate mother, ambles along with such low-key, easygoing humor that it's almost a shock to the system: Where are the hamburger phones, the rat-a-tat pop culture references, the porn?

All have been left behind in the service of what is a far more observant, if uneven, comedy of 21st-century manners. As "Baby Mama" opens, Kate Holbrook (Fey) explains how at 37 she has stopped pressing the snooze button on her biological clock and, after climbing the corporate ladder of the groovy Whole Foods-like company she works for, she's finally ready to reproduce. After a swiftly moving sequence wherein she discovers she possesses a T-shaped uterus and that adoption will take years, she lands in the office of a surrogate pregnancy broker, played by Sigourney Weaver with hilarious superciliousness.

Weaver's character puts Kate in touch with Angie (Poehler), a hard-edged, slightly ditzy dame who has decided to rent out her womb at the advice of her loser of a common-law husband Carl (Dax Shepard). When she meets Kate, Angie primly explains that she met Carl "the summer after I discontinued high school," and "Baby Mama" continues in this vein, almost but not quite burying its jokes in the subtle, revealing turn of the phrase.

When Angie moves in with Kate, "Baby Mama" becomes a classic odd-couple romantic comedy, with the two women bickering, bonding, breaking up and reconciling. In a subplot, Kate meets a terrific guy named Rob (Greg Kinnear) who runs a smoothie shop (he routinely rails against Jamba Juice as "corporate juice pimps"), copes with the disapproval of her haughty mother (played by Holland Taylor at her most fabulously pompous) and manages the eccentricities of her boss, a pretentious gray-ponytailed guru named Barry, who says things like "Time is love" and "I was just talking to Jimmy Buffett about trans fats."

Barry is portrayed by Steve Martin, who, like everyone else in this production, makes the gratifying decision to underplay. Whereas Fey and Poehler could easily have become caricatures -- Fey ratcheting up the neuroses of her character on "30 Rock," for example, or Poehler channeling Jaime Pressly on "My Name Is Earl" -- instead each actress gives her character her dignity, grounding her as a recognizable human being. Even within the contrived confines of its genre, "Baby Mama," which was written and directed by Michael McCullers, rings with a certain degree of truth, whether about motherhood, competition or economic class. When the film reaches the inevitable confrontation in which everything goes awry, Kate's outburst toward Angie stings with a startling amount of venom.

A very small but crucial moment within that scene is provided by Romany Malco as Kate's doorman, who acts as sort of a sotto voce chorus throughout the proceedings. Best known for his wonderful work on the cable show "Weeds," Malco embodies the kind of unforced warmth that suffuses "Baby Mama" and makes it such a welcome alternative to the desperation and self-loathing of the Judd Apatow canon, or the compulsive verbosity of "Juno." This ease is even reflected in McCullers's choice to set "Baby Mama" in Philadelphia, a stately, attractive city with nothing to prove. (Which isn't to say that "Baby Mama" doesn't feature its share of raunch: There are plenty of jokes involving sex, childbirth and various and sundry lady parts.)

Finally, "Baby Mama" belongs to Fey and Poehler, and the question of whether viewers will enjoy it probably comes down to how they feel about the two actresses, both of whom play to their strengths here (Poehler is a far better physical comedienne, especially in her facial expressions). For those who crave mannerisms and shtick, and who like their jokes set up and knocked out with plenty of arrows and quote marks, "Baby Mama" may fall as flat as one of the character's fake bellies. But audiences alive to the modest charms of its take on female friendship will be rewarded with at least a few quiet chuckles.

Baby Mama (96 minutes, at area theaters) is rated PG-13 for crude and sexual humor, profanity and a drug reference.