This week-end opens another comedy, this time focusing on the relationship of two women, “Baby Mama.”

The movie is both written and directed by Michael McCullers and features “30 Rock’s” Tina Fey as the protagonist, Kate, a 37-year old executive woman who suddenly acknowledges her desire to become a mother. Apparently Kate heard the tic-tac of her biological clock a little too late, as her odds of getting pregnant are virtually inexistent. Therefore she starts looking for an alternative and turns to a surrogacy center run by Chaffee (Sigourney Weaver).

One hundred thousand dollars later, Kate meets with the surrogate mother of her baby, Angie (Amy Poehler of “Saturday Night Live”). Amusement is generated by the antagonism between the two women, Kate, a vice president of a natural food supermarket chain, focused on her career, and Angie, a slacker coming from the working class, fond of junk food and video games. However, the gap is bridged by the initial click between them. Angie splits up with her common-law husband (Dax Shepard) and moves in with Kate in her fancy Philadelphia apartment, for the sake of the baby.

Besides the constant frictions between them, there are other funny moments in the movie. Kate’s boss, egocentric and eccentric, Barry (played by Steve Martin) sports a New Age-y ponytail indulges his employees with five whole minutes of staring into his eyes as a reward. Then there’s also the doorman, nosy Oscar (Romany Malco of “The 40-Year-Old Virgin”) who is always ready to prove his wisdom.

Even though there are a great number of elements that remind of other movies, such as “Parenthood” or “Baby Boom,” “Baby Mama” is entertaining enough not to accuse it of lack of originality.