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
MC cause of anovulation is? 
Select and explain. 
A. PCOS, B. Hyperprolactinemia, C. Premature ovarian failure, D. Low ovarian reserves
A: PCOS
Answer: A: PCOS 
Explanation: Ans. is 'a' i.e.,PCOSAnovulation and ovulatory dysfunction can be caused by a number of factors.The most common cause of ovulatory dysfunction is polycystic ovarian syndrome, or PCOS.Other potential causes of irregular or absent ovulation:Obesity Underweight Extreme exerciseHyperprolactinemia Premature ovarian failure Perimenopause, or low ovarian reservesThyroid dysfunction Extremely high levels of stress