impregnate vs procreate

impregnate

verb
  • To fertilize. 

  • To saturate, or infuse. 

  • To fill pores or spaces with a substance. 

  • To cause to become pregnant. 

procreate

verb
  • To reproduce. 

  • To originate, create or produce something. 

  • To beget or conceive (offspring). 

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