The phrase "unnatural position" refers to a posture or stance that is not typical or normal for a person's body or behavior. It can also mean a situation that is not in accordance with natural or expected circumstances. Full definition
Sitting in a chair is a very unnatural position for the spine. (truehealthct.com)
Their feet are twisted into very unnatural positions which takes away from the great looks they are wearing. (40plusstyle.com)
The author argues that unnatural positions make labour and birth more painful and difficult for modern women than it was for their ancestors. (pinterandmartin.com)