postpartum vs postpartum depression

postpartum

noun
  • The period immediately following childbirth. 

adj
  • Of a mother: after giving birth (often defined as within 30 days after childbirth). 

adv
  • After giving birth. 

postpartum depression

noun
  • Depression experienced by a parent, usually the mother, after childbirth. 

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