While that's a cool idea, I only see one problem: how would you convey that in dialogue without destroying the pacing of the movie or sounding unnecessarily expository?

Obi-Wan: Let her go!

Vader: No! As this unborn child might overthrow me as is the case with all Sith based on my five minute introduction into Sith culture proves, I must kill her so the child usurper will die as well.

Obi-Wan: You sick monster! Let's fight!

Vader: Hold on just a few more seconds. She still has a little bit of oxygen left.

^_~