miscarriage vs stillbirth

miscarriage

noun
  • The spontaneous natural termination of a pregnancy, especially before it is viable; the fatal expulsion of a foetus from the womb before term. 

  • A failure; a mistake or error. 

stillbirth

noun
  • The birth of a dead fetus after 20 weeks of gestation. 

  • The birth of a dead fetus; the delivery of an infant which is dead at birth. 

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