Heigl plays a TV journalist who becomes pregnant after a one-night stand with an unemployed slob, played by Seth Rogen.
The movie was a massive hit and helped Heigl's earnings rise from $300,000 to $6 million.
But she tells Vanity Fair magazine, "It's a little sexist. It paints the women as shrews, as humorless and uptight and it paints the men as lovable, goofy, fun-loving guys.
"It was hard for me to love the movie."
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