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Fans of 30 Rock and devotees of Tina Fey should know an important detail before buying a ticket for Baby Mama: The comedy, co-starring Fey and Saturday Night Live’s Amy Poehler, was not written by the current It Scribe. Expectedly, then, it’s rarely as laugh-out-loud funny as Fey’s TV series or even the duo’s previous big-screen pairing, 2004’s Mean Girls (which Fey did write). But compared to the usual SNL-goes-to-the-movies train wrecks—or, say, Made of Honor—this pleasant, relatively original film is a comedy master class.

And surely writer-director Michael McCullers (a screenwriter for the Austin Powers series) let his stars have some fun with his odd-couple story about surrogacy. Kate (Fey) is a 37-year-old executive of an organic-foods market who wants to have a child “now.” With no man in her life, low odds of getting approved to adopt, and an oddly shaped uterus that her fertility doctor “just doesn’t like,” Kate decides that her only option is to find what her doorman, Oscar (The 40-Year-Old Virgin’s Romany Malco), has a ready slang term for: “You pay the bills, she has the baby—that’s called a baby mama. Ask any man in Philadelphia.”

After a meeting with an ironically fertile surrogacy agent (Sigourney Weaver, gamely making herself the target of age jokes), Kate is introduced to Angie (Poehler), a trashy junk-food inhaler whose only motivation in carrying someone else’s kid is the paycheck. When Angie leaves her deadbeat boyfriend (Dax Shepard), Kate takes her in, and both of the women’s prenatal glow dims as they get to know each other. (Angie, for instance, declares she’d “rather get hit in the face” than indulge in Kate’s stockpile of healthy food.)

Fey mostly plays it straight here, though her Kate is not above translating a birthing coach’s instructions to “pwep your perwanium with EVOO”—yes, she’s got a Baba Wawa speech impediment, and it’s childish but still kinda amusing—as, “I think she wants me to rub olive oil on your taint.” But Poehler, who’s often grating in her SNL skits, pulls off the funniest bits here: Angie’s fake-out offer of gas money to Kate is brilliant, and Poehler spits—food, vitamins, more food—like a pro. And Juno MacGuff, for all her logorrheic wisecrackery, could never yell out a more believable labor line than “It feels like I’m shittin’ a knife!”

Even Kate’s requisite budding relationship (the suitor played by Greg Kinnear) is sharply drawn, particularly a terrific scene that highlights the universal moment when a casual remark can make a person previously blushing with puppy love suddenly want to run for the door. Like most of Baby Mama, it’s not gut-busting. But after a parade of romantic comedies that shoot one-liners with machine guns or twist circumstances to contrivance, it’s a relief to enjoy a story that just feels natural.