postnatal depression vs postpartum

postnatal depression

noun

  • 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. 

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