This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Methods - Progestogen-Only Contraception, Subject name: Gynaecology & Obstetrics
Progesterone pills act by which of the following mechanism? 
Select and explain. 
A. Thickening of cervical mucus, B. Inhibiting ovulation, C. Causing aseptic inflammation in endometrium, D. Destruction of embryo
A: Thickening of cervical mucus
Answer: A: Thickening of cervical mucus 
Explanation: Ans. a (Thickening of cervical mucus). (Ref. Dutta, Obstetrics.4th/586, William Obstetrics 21st/1531)MINIPILLS (Progesterone Only Pills)# E.g., levenorgestrol 30 meg, norethistrone 350 meg.- They act by thickening the cervical mucus.- It is very useful as a emergency contraception.# Advantages- Side-effects attributed to estrogen are totally eliminated.- Lactational pill- No "on and off " regimen.- May be used by patients witha) Hypertension, Fibroid, DM,b) Epilepsy, Smoking, Thromboembolism.- Ideal for patients with sickle cell disease as progesterone is thought to treat bony crises.# Side-effects- Amenorrhea, at times breakthrough bleeding- All side effects are attributed to progesterone may be evident- Simple cyst of ovary# Failure rate = 0.5-2 HWY.