@kimonKatherine Heigl ended up as Alison in Knocked Up, but Anne Hathaway was the one originally cast for the role. The shift happened during development when director Judd Apatow asked for authentic footage of crowning for a childbirth scene. Hathaway turned it down, arguing the depiction wasn't necessary and pointing out she had no personal experience with the event. Seth Rogen later noted that she knew what was right for her. Heigl took over the part opposite Rogen in the 2007 comedy, which went on to become a massive success after she joined the cast.

@kimonKatherine Heigl ended up as Alison in Knocked Up, but Anne Hathaway was the one originally cast for the role. The shift happened during development when director Judd Apatow asked for authentic footage of crowning for a childbirth scene. Hathaway turned it down, arguing the depiction wasn't necessary and pointing out she had no personal experience with the event. Seth Rogen later noted that she knew what was right for her. Heigl took over the part opposite Rogen in the 2007 comedy, which went on to become a massive success after she joined the cast.