Neither Tina Fey nor Amy Poehler seems invested in Baby Mama

Could have sworn I've seen this episode of Baby Mama before, when it aired on Tina Fey's prime-time gig, 30 Rock. It was funny the first time around, when Fey, as late-night-TV exec Liz Lemon, found herself drawn to the sound of cooing and the scent of baby powder. After a poorly placed phone call to the world's worst fertility/meth-addiction doctor, Lemon wound up snatching an adorable tyke from a hairdresser — totally by accident, but still dark, weird stuff.

Baby Mama>extends the joke, then softens it, then smothers it in its crib — an unpleasant picture perhaps, but not any more disagreeable than the phrase "Produced by Lorne Michaels."

Pairing Fey with her former "Weekend Update" co-anchor Amy Poehler, Baby Mama's little more than> Tommy Boy Mean Girls, which Fey wrote and appeared in alongside Poehler. But Fey didn't write this one; first-time director Michael McCullers did — he of such duds as Thunderbirds and Undercover Brother, which only felt like a Lorne Michaels production.

Fey's now called Kate Holbrook, and instead of an NBC TV exec, she's a VP at a Whole Foods knockoff called Round Earth. She works for a ponytailed boss, played by Steve Martin as a puffy hippie-dippy dope who rewards his execs with things like five minutes' worth of uninterrupted eye contact. (Martin hasn't been so deadpan or dead-on in ages.)

Kate, of course, wants a baby: She visits a sperm bank, consults doctors, and plasters her apartment with Post-it notes bearing such think-positive aphorisms as "Yes! Be Fertile!" But as the Coen Brothers put it in Raising Arizona, her insides are a rocky place where a man's seed can find no purchase. Kate outsources her pregnancy for $100,000 and winds up with a "dumb white-trash" couple on her doorstep: Angie Ostrowiski (Poehler) and her husband Carl (Dax Shepard). Poehler doesn't seem sure what to do with Angie, who occasionally speaks in a hillbilly accent — unless it disappears altogether, and she's just Amy Poehler killing time till the next commercial break.

Ultimately, the movie exists solely to reunite a winning comic duo: two women so singularly in sync that, during their stint on "Weekend Update," they genuinely laughed at each other's jokes, despite their no doubt well-worn familiarity come showtime. Kate and Angie are just Tina and Amy goofing around — drunk-dancing, crooning along to video-game karaoke, and, once more, finishing each other's sentences. I'd rather watch MILF Island.