Emergency contraceptive pills (ECPs) with levonorgestrel 1.5 mg act PRIMARILY by which mechanism?
- A Preventing implantation of a fertilised embryo
- B Causing luteolysis and termination of early pregnancy
- C Inhibiting or delaying ovulation ✓
- D Increasing tubal ciliary motility to prevent fertilization
Correct answer: C. Inhibiting or delaying ovulation
Explanation
The primary and most well-established mechanism of levonorgestrel emergency contraceptive pills is inhibition or delay of ovulation, particularly by suppressing the LH surge. Evidence does not support a post-fertilization effect (preventing implantation) as a significant mechanism. This is an important distinction for counselling and ethical considerations. Luteolysis is the mechanism of mifepristone (RU-486), which is a medical abortifacient.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.