This is an expanded version of a comment I left on Ross Douthat's blog post which mysteriously got deleted. (Feel free to send him hate mail regarding his censorship.)
Knocked Up is only a cog in a big Hollywood machine opposed to abortion rights. Whether or not one supports abortion rights is besides the point, it's a fact that Hollywood is on the side of the anti-abortion movement. This is fact is demonstrated by the observation that no woman in a movie or TV show ever has an abortion. (The only exception I know about, mentioned in the Dana Stevens piece, is the character Claire in the HBO series Six Feet Under.)
This Hollywood portrayal is in opposition to the reality of abortion statistics. According to the Alan Guttmacher Institute, "[n]early half of unintended pregnancies and more than one-fifth of all pregnancies in the United States end in abortion" (link). While one movie, by itself, could be seen as an anomaly, there have been a very large number of unintended pregnancies in the universe of movies and television shows, and in every case except in Six Feet Under, the woman either decides to have the baby or she has a fortuitous miscarriage.
Unfortunately, the Alan Guttmacher Institute doesn't keep track of what percent of upper middle class single career women in a liberal state like California who become accidentally pregnant by a total loser she'd never marry wind up obtaining abortions, but I suspect that the number would be close to 95%. Thus the movie Knocked Up, by presenting the 5% exception as if it were the norm, is most certainly making a political statement.
I also think it's interesting to contrast the absence of abortion in Hollywood with the surge of gay sex. It seems like everytime I watch a movie or turn on the television, I see two men having sodomy (or at least the suggestion of sodomy--and I use the word sodomy because "sex" is supposed to be reserved for the act between men and women). The reason I stopped watching Six Feet Under, despite its realistic portrayal of abortion, is because I just couldn't stand seeing David kissing and fondling other men, week after week.
The disparate treatment of gay sex and abortion shows that the gay lobby is winning and the pro-abortion lobby is losing. If abortion is so horrible that it can't be portrayed even in an R-rated movie, then it's inevitible that abortion will eventually become illegal.
The problem is that Hollywood has it backwards. Sodomy is bad because it spreads AIDS. According to the CDC, "at the end of 2003, an estimated 1,039,000 to 1,185,000 persons in the United States were living with HIV/AIDS, with 24-27% undiagnosed and unaware of their HIV infection." The CDC also makes clear that AIDS, in the United States, is being spread by gay men. 48% of new AIDS diagnoses in the United States is attributed in sum or part to "male-to-male sexual contact." Gay men are only 1% of the population (I'm generously assuming that 2% of men are gay and half the population is male) yet they account for nearly half of AIDS cases.
Why is AIDS a problem for people who don't engage in risky behaviors? Because (1) everyone is paying for the high healthcare costs of people with AIDS, both through higher healthcare premiums and higher taxes; and (2) in 2005, 540 innocent people were diganosed with AIDS, and by innocent I mean those who didn't engage in any risky behavior.
Abortion, on the other hand, is good for America. Poor women have more abortions than rich women, so abortion has a eugenic effect. (Although rich women are more likely to get an abortion if they become accidentally pregnant, rich women are far better than poor women at using birth control so they are unlikely to need an abortion in the first place.) Single women who have out-of-wedlock children often wind up on welfare, so abortion saves the taxpayer money and allows the poor woman to contribute to society by working instead of mooching off of society by raising their kids on the public dole. According to the book Freakonomics, abortion even lowers crime.