It's hard not to set high expectations for a movie co-starring America's funniest women, Tina Fey and Amy Poehler. But unless you resist doing so, you're unlikely to enjoy this movie. Even their dead-on comic timing can't save the movie from unnecessary plot twists, toilet jokes and an overly abrupt ending. Fey plays Kate, a 37-year-old, straight-laced career woman who desperately wants a baby. When she learns she can't get pregnant, she hires a surrogate mother to have the baby for her. This 'baby mama' is her complete opposite: Angie (Poehler) is a childish, trashy, unemployed woman forced to move in with Kate. Their odd pairing allows for some slapstick humour. Unfortunately Fey and Poehler played almost the same juxtaposed characters in their first movie collaboration, Mean Girls. If you've never seen them together, you'll be amused, but it is far too predictable for those who have. Fortunately, Hollywood veterans Sigourney Weaver and Steve Martin make hilarious cameos, doing much to save the film. But the rest of the movie suffers from an abrupt conclusion and unexplained premises. They may be minor details, but their existence means the movie falls far below expectations.