Emergency contraception with Levonorgestrel 1.5 mg is MOST effective when taken:

• A Within 72 hours (efficacy decreases with time but remains effective up to 120 hours)
• B Within 120 hours with uniform 89% efficacy throughout the period
• C At any time until next menstrual period
• D Within 24 hours of unprotected intercourse (>95% efficacy) ✓

Explanation

Levonorgestrel emergency contraception is most effective when taken as early as possible after unprotected intercourse: within 24 hours (>95% pregnancy prevention), 24–48 hours (~85%), 48–72 hours (~58%). It can be used up to 72 hours (not 120 hours — that applies to ulipristal acetate and Cu-IUD). The 'uniform 89% efficacy' claim is an average, not a constant. The primary mechanism is inhibiting or delaying ovulation; it has minimal effect on implantation. This timing-dependent efficacy gradient is a tested clinical point.

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.