.”Baby Mama” features Kate Holbrook (Tina Fey), a 37-year-old, single working woman. Though successful and competent in her endeavors into the world of organic food production and sale, she is plagued with an infertile “t-shaped” uterus. The inevitable ticking of Holbrook’s biological clock evolves into fear that she’ll never marry or have children. Until now, she hadn’t considered that focusing on her career would result in a childless existence. After desperate attempts at adoption and in vitro fertilization, Fey turns to Angie Ostrowiski (Amy Poehler), a hysterically trashy surrogate mother, in an attempt to create a family she couldn’t on her own.

It’s really no surprise that Fey and Poehler are a dazzling duo. The witty team delivers PG-13 humor galore. Poehler and Fey sing karaoke, take birthing classes and hit the clubs. Several of the film’s best moments involve Fey’s boss, an earthy, wig-clad Steve Martin.

Fey is an unlikely heroine, and her sarcasm is a credit to the film. American cinema finally experiences a departure from the barbie-like businesswomen that so often plague the silver screen. With Greg Kinnear co-starring as Fey’s juice-making ex-lawyer love interest, “Baby Mama” successfully attacks the romantic comedy from a more realistic angle.

The film runs smoothly until the final 20 minutes. The finale is a disaster. In an effort to depart from the expected, “Baby Mama” is disappointing and oversimplified. The film would have been most effective if it would have embraced the most obvious path of direction.

Sadly, its talent and wit cannot overcome the poor plotline. “Baby Mama” is good for a laugh, but not a second watch, unless you’d favor turning the film off early.