abortus vs stillbirth

abortus

noun
  • An aborted fetus, especially one aborted in early pregnancy. 

  • An abortion. 

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 abortus and stillbirth occurred in a corpus of books? (source: Google Ngram Viewer )