25 things you didn’t know about your favorite rom-coms

Knocked Up: An Oscar winner quit over birth scenes

Knocked Up was a modern romantic comedy that was aimed more at men than women, something that doesn’t happen often. The film was Seth Rogen’s first starring role, alongside Katherine Heigl, as a couple whose drunken one night stand turns into an unplanned pregnancy.

Ben (Rogen) and Alison (Heigl) couldn’t be more different. Ben is a stoner with no job, and Alison works for E! Entertainment. Alison has her life planned ahead of her, and Ben has no ambition whatsoever, besides starting an adult-themed website with his friends. Once Allison finds out she’s pregnant, the two try to make the relationship work, despite having absolutely nothing in common.

The movie, however, was almost very different, because Katherine Heigl wasn’t the original star. Oscar-winner Anne Hathaway was cast as Alison before Heigl, but the star left because of creative differences with director Judd Apatow. Apatow wanted to use real footage of a woman giving birth for the birthing scene in the movie to make it more realistic, and Hathaway refused.

Once Hathaway was out, the casting team had a lot of other options for the role of Alison. Some of the other actresses considered for the lead included Rachael Leigh Cook, Cameron Diaz, Drew Barrymore, Claire Danes, Juliette Lewis, Uma Thurman and Renée Zellweger. All of them either dropped out or were fired. The role was even offered to Christina Aguilera, but she chose to focus on her music instead.

Luckily, they settled on Katherine Heigl, and the movie became a modern classic!