text: Niddah 44 b provides that "A girl of the age of three years may be betrothed by intercourse" while Sanhedrin 84b
  
  http://www.come-and-hear.com/sanhedrin/sanhedrin_84.html#PARTb
  
  is silent on abortion.
  
  But, since we are not pre-Christian era Jews, let's examine this as though we were Catholics.
  
  Self-defense involves an action directed toward an unjust aggressor so to render the aggressor unable to cause harm (see CCC 2265).
  
  Self-defense also requires intending only stopping the aggression, not killing the aggressor.
  
  But direct abortion is always directed at killing the fetus and the fetus does not meet the definition of an aggressor. The fetus is unable to will to be born, or will to cease causing harm, or in fact exercise any control at all.
  
  http://www.papalencyclicals.net/Pius11/P11CASTI.HTM
  
  paragraph 64