Anti-feminist propaganda.
At the beginning of this film, we are presented with a light-hearted, carefree couple who choose to go on tropical vacations for Christmas every year, as opposed to visiting their dysfunctional families.
We find out that they are child-free and marriage-free by choice, and quite happily at that. Nowhere in the first half of the film do we encounter Reese Witherspoon's character struggling internally with want for a child or marriage. The only dilemma of the story is that they have to spend a day with their crazy relatives, which would have itself made for an endearing, funny movie.
In a standard anti-feminist turning point, we find out that all of a sudden, Reese is just DYING to have a child, although she never expressed this want before. If, at the beginning of the movie while they were explaining their situation to the ballroom dancing couples, did Reese show us a "look" that she internally disagreed with Vince, we might have understood, but this is TOTALLY out of the blue.
Within these last few hours of spending time with little hellions, Reese decides that she wants a child SO BADLY that she leaves her boyfriend for not agreeing with her sentiments. The audience (myself) is very clearly confused.
They make up, yadda yadda yadda, and a year later they have a baby. WHY was this plot point introduced? It was completely unnecessary. The only reason that I can personally think of is that the director/writer wanted to make sure that the childfree-by-choice women watching know that they are WRONG and being childfree is WRONG, and your partner/husband will never be completely committed to you without one. They want to show you that Reese's character was REDEEMED at the conclusion of the film because she had a child.
I know that some of you may think that I'm reading too far into this because it's a comedy, but I didn't spend hours after my initial viewing of this movie thinking about it. Its true message unraveled during every scene.