This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
Which of the following is true regarding early deceleration in a CTG (cardiotocography)? 
Select and explain. 
A. It is due to increased vagal tone in the foetus, B. It is due to foetal hypoxia, C. It is due to raised BP in the mother, D. It is due to cord compression
A: It is due to increased vagal tone in the foetus
Answer: A: It is due to increased vagal tone in the foetus 
Explanation: Early deceleration coincides with the uterine contraction and is a result of increase in vagal tone since the foetal intracranial pressure rises with uterine contraction. Ref: Oxford Handbook of Clinical Specialities, 8th Editio, Page 45.