pregnancy vs prolificacy

pregnancy

noun
  • The progression of stages from conception to birth. 

  • The condition of being pregnant; an instance of this. 

  • The period of time this condition prevails. 

prolificacy

noun
  • Great fertility. 

  • Producing of a large number of literary or artistic works. 

How often have the words pregnancy and prolificacy occurred in a corpus of books? (source: Google Ngram Viewer )