fetal vs initiatory

fetal

adj
  • Pertaining to, or connected with, a fetus. 

initiatory

adj
  • Of or pertaining to initiation 

  • inceptive, initial, inaugural or introductory 

noun
  • An introductory act or rite. 

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