Complex sentence: The film was completed three months before its release, but Warner Bros. decided to delay the release of the film until after the birth of Joan Blondell's child, so that Blondell would not be off the screen for too long a period.
Split into simpler sentences: The film was completed three months before its release, but Warner Bros. decided to delay the release of the film until after the birth of Joan Blondell's child. So that Blondell would not be off the screen for too long a period.