lying-in vs parturition

lying-in

noun
  • The final stages of pregnancy; accouchement. 

  • A period of postpartum confinement, typically a month or longer, formerly common in Europe and still practiced in some parts of the world. 

adj
  • of, or relating to childbirth or postpartum confinement 

parturition

noun
  • The act of giving birth; childbirth. 

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