childbirth vs lying-in

childbirth

noun
  • The fact or action of giving birth to a child, as the culmination of pregnancy. 

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 

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