morning sickness vs motion sickness

morning sickness

noun
  • Early morning nausea and vomiting as a symptom of pregnancy. 

motion sickness

noun
  • A feeling of nausea or dizziness caused by a disagreement between visually perceived movement and the vestibular system's sense of movement; typically resulting from travel in a vehicle such as a ship or car. 

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