Obstetrics & Gynaecology – MCQ 56 – Mechanisms of action of oral contraceptive pill

All of the following mechanisms of action of oral contraceptive pill are true, except:
A. Inhibition of ovulation
B. Prevention of fertilization
C. Interference with implantation of fertilized ovum
D. Interference with placental function

Correct answer : D. Interference with placental function

Mechanism of action of oral contraceptive pills:

• Prevents ovulation by inhibition of LH surge
• Induce atrophic changes in endometrium, preventing nidation
• Thickening of cervical mucus preventing entry of sperms
• Increases tubal motility, so that the fertilized egg reaches uterine cavity before the endometrium is receptive for implantation