pregnancy vs richness

pregnancy

noun
  • The period of time this condition prevails. 

  • The progression of stages from conception to birth. 

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

richness

noun
  • The state of having many examples or cases; abundance; profusion. 

  • The result or product of being rich. 

  • The number of types in a community. 

  • The state or quality of being rich; wealthiness, wealth. 

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