The SINGLE most important contraceptive mechanism of the combined oral contraceptive pill is:
- A Suppression of the mid-cycle LH surge, thereby inhibiting ovulation ✓
- B Thickening of cervical mucus
- C Induction of endometrial atrophy
- D Impairment of tubal peristalsis
Correct answer: A. Suppression of the mid-cycle LH surge, thereby inhibiting ovulation
Explanation
The progestin component suppresses cyclic GnRH pulsatility, blocking the mid-cycle LH surge, while estrogen suppresses FSH and prevents follicular recruitment; together they reliably inhibit ovulation, which is the dominant contraceptive effect. Cervical mucus thickening is the principal mechanism of progestin-only methods and a secondary effect here, killing distractor B. Endometrial changes and altered tubal motility contribute marginally and never constitute the main mechanism.
Reference: Ganong's Review of Medical Physiology, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.