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
The clinical diagnosis of threatened aboion is presumed when a bloody vaginal discharge appears through a closed cervical os during: 
Select and explain. 
A. First half of pregnancy, B. Second half of pregnancy, C. Third trimester, D. All
A: First half of pregnancy
Answer: A: First half of pregnancy 
Explanation: A;First half of pregnancy