This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
What is the effect of Progesterone only pills? 
Select and explain. 
A. Completely suppresses ovulation, B. Thin lining of uterus, C. Thick cervical mucus, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: * Progestogen-only pills / Progestin-only Pills (POP) / Morning after pills - * Contraceptive pills * Contain only synthetic progestins & doesnt contain estrogen. * Mechanism: * Mucus thickening in neck of womb: # Penetration of sperm to reach egg and womb becomes difficult. * Prevents ovulation: * Lining of the uterus becomes thin # Feilized egg implantation is prevented * Advantages: * Doesn't interfere with breastfeeding * Also helps in premenstrual symptoms and painful periods REF : SHAW GYNECOLOGY