expected date of confinement vs maturity

expected date of confinement

noun
  • due date; The date on which a pregnant woman is expected to give birth. 

maturity

noun
  • Date when payment is due. 

  • The state of being mature, ready or ripe. prime state of productibility and self expression. 

  • When bodily growth has completed and/or reproduction can begin. 

  • The state of a debt obligation at the end of the term of maturation thereof, once all interest and any applicable fees have accrued to the principal. 

How often have the words expected date of confinement and maturity occurred in a corpus of books? (source: Google Ngram Viewer )