An upcoming Jack Nicholson and Reese Witherspoon film has delayed its production after one of its stars unexpectedly went into labor prematurely.

According to RadarOnline, a pregnant-in-real-life Kathryn Hahn is playing a pregnant secretary in "How Do You Know." She unexpectedly went into labor Saturday on the set of the film and gave birth to daughter Mae after two days.

Since her due date was projected as September, producers of the film had been thrown into panic mode. They expected Hahn to give birth after the filming wrapped up, but since she gave birth earlier than expected and during production, they are said to be likely replacing her with another actress and will re-shoot all her scenes.

Paul Rudd and Owen Wilson also stars in the James L. Brooks film.