[1] This can lead to an obstruction of the airway, restricting the flow of air and preventing gaseous exchange, which then causes hypoxia, which is life-threatening.

[2][3] This is especially true for unconscious pregnant women; once turned on to their left side, pressure is relieved on the inferior vena cava, and venous return is not restricted.

It is not necessarily used by health care professionals in an institutional setting, as they may have access to more advanced airway management techniques, such as tracheal intubation.

The International Liaison Committee on Resuscitation (ILCOR) does not recommend one specific recovery position, but advises on six key principles to be followed:[4] The earliest recognition that placing unconscious patients on their side would prevent obstruction of the airway was by Robert Bowles, a doctor at the Victoria Hospital in Folkestone, England.

This thinking was, however, not widely adopted, with surgical textbooks 50 years later still recommending leaving anaesthetised patients in a supine position.