Altitude sickness and Morning sickness

Altitude sickness noun - Effects (as nosebleed or nausea) of oxygen deficiency in the blood and tissues at high altitudes.

Morning sickness and altitude sickness are semantically related. In some cases you can use "Morning sickness" instead a noun phrase "Altitude sickness".

Morning sickness noun - Nausea early in the day; a characteristic symptom in the early months of pregnancy.

Altitude sickness and morning sickness are semantically related. You can use "Altitude sickness" instead a noun phrase "Morning sickness".