It's fertile territory

"Baby Mama," which was written for Fey and her "Weekend Update" co-anchor Amy Poehler by "SNL" alumnus and "Austin Powers" screenwriter Michael McCullers, who also directs, is blithely unconcerned with gender-baiting. In fact, the movie hardly allows itself any sharp moments at all -- it's much too sweet-natured to be cruel, and much too cheerful to be angry. It probably could have pushed a few more buttons, but "Baby Mama" aims to please and succeeds.

Fey plays Kate Holbrook, a 37-year-old single businesswoman who is suddenly overcome with the desire to have a baby. She's not a basket case, she's just a fool in love with little, bald, fat incontinent creatures. She tries a sperm donor, but the insemination doesn't take. Kate has an unfortunate T-shaped uterus, and her dreams of motherhood are dashed. Enter Angie Ostrowiski (Poehler), an underachiever from South Philadelphia turned surrogate mother.

Considering the premise, "Baby Mama" might have gone the skewering route, taking on all that is over-the-top about technology-assisted, socially revolutionary baby-making and rearing. And it does get in some jabs. When it lets the mean zingers fly, it's mercilessly on-target. In one scene, Kate and Angie meet to work out some issues with Chaffee Bicknell (Sigourney Weaver), the formidable, clearly post-menopausal head of the surrogacy agency that has brought them together. When Chaffee smugly announces that she's expecting, Kate and Angie allow their shock to register. Then Angie mutters under her breath, "Expecting what? A Social Security check?"

There are other moments like that: Angie's IVF is played like a romantic scene, set to the song "Endless Love," as a fertility doctor (John Hodgman) preps the turkey-baster-sized syringe in the background; a mother in a playground tells her kids it's time for their play-date with Wingspan and Banjo; Kate's callous mom (whose liver spot medication may have caused her daughter's uterus problems) begs her not to adopt a black baby just because the celebrities are doing it.

But most of the time, "Baby Mama" stays away from satire and goes for smiles as often as it goes for laughs. "Baby Mama" is a love-fest, a good-natured buddy comedy whose humor comes from the odd-coupling of Angie and Kate, who wind up living together after Angie leaves her trashy common-law husband, Carl (Dax Shepard). Poehler and Fey play against stereotype with sweet, unexpected results.

Basically, Fey is Martin to Poehler's Lewis. When Angie first shows up in Kate's life, it's in a pigpen cloud of bad choices and chaos. But McCullers doesn't milk the white-trash bashing for long, and Angie mellows into a three-dimensional character in fairly short order. What she doesn't lose is that lunatic edge that makes her so funny. Next to Fey's even-tempered, good girl, Poehler is a loose cannon. As Kate complains to her sister Caroline, an under-used (where has she been?) Maura Tierney, after Angie first moves in, "It's like living with a child!" Pregnant and surrounded by out-of-control kids, Caroline reminds her that she soon will be living with an actual child, so she'd better get used to it.

If Angie is a nice respite from the usual blue-collar representations, Kate is an especially welcome antidote to the prevalent movie stereotype of the working woman who forgot to have a baby. Unlike, say, Helen Hunt's character in this week's other desperate non-housewife movie "Then She Found Me," Kate is a warm, calming, grounding presence. Her brand of desperation -- if you can even call it that -- is gooier, more distracted, more romantic than the hard-edged kind you usually get.

The men in Kate's life, aside from a hilariously cheesy, mustache-sporting ex played by Will Forte, are limited at first to co-workers, in particular her boss, Barry, a super-groovy health food chain owner played by Steve Martin. Martin and Weaver make up the smug boomer contingent of the movie, the we-can-have-it-all types who make life so hard for people like Kate. (Kate's boss rewards her for a job well done with "five minutes of uninterrupted eye contact.") As annoying as Barry is, Kate treats him with respect and affection.