mummy vs surrogate mother

mummy

noun
  • mother. 

  • Any naturally preserved human or animal body. 

  • An embalmed human or animal corpse wrapped in linen bandages for burial, especially as practised by the ancient Egyptians and some Native American tribes. 

  • A reanimated embalmed human corpse, as a stock character in horror films. 

  • A substance used in medicine, prepared from mummified flesh. 

surrogate mother

noun
  • A woman who gives birth to a child not her own, with the intent to give that child up to at least one of the biological parents once it is born. 

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