mishap vs stillbirth

mishap

noun
  • An accident, mistake, or problem. 

  • Evil accident; ill luck; misfortune; mischance. 

stillbirth

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

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

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