This Viva relates to the respiratory changes of pregnancy at term, hypoxaemia and the foetal 
circulation. 
Q 1. Describe the respiratory changes in pregnancy at term.
Subsequent questions sought a description of ABG at term pregnancy, physiological mechanism 
to explain an increased A-a gradient, causes of a low PaO2 in a patient with a normal A-a 
gradient, the response of hypoxemia to supplemental O2 when the A – a gradient is normal and 
when abnormal, and a description of the foetal circulation and the changes that occur at birth.