biological mother vs old woman

biological mother

noun
  • The woman from whom one inherits half of one's DNA and who is the source of one's mitochondrial DNA. 

old woman

noun
  • One's wife. 

  • One's mother. 

  • An elderly woman. 

  • A person (irrespective of age or sex) who is always complaining about his or her situation. 

  • The plant sea wormwood. 

How often have the words biological mother and old woman occurred in a corpus of books? (source: Google Ngram Viewer )