Emergency contraception using levonorgestrel 1.5 mg (single dose) must ideally be taken within what timeframe after unprotected intercourse to maximize efficacy?
- A Within 72 hours ✓
- B Within 24 hours
- C Within 48 hours
- D Within 120 hours
Correct answer: A. Within 72 hours
Explanation
Levonorgestrel 1.5 mg (progestogen-only emergency contraception) is most effective when taken within 72 hours (3 days) of unprotected intercourse, reducing the risk of pregnancy by approximately 85–89%. Efficacy declines with time: 95% if taken within 24 hours, 85% within 24–48 hours, and 58% within 48–72 hours. Ulipristal acetate (ella) is effective up to 120 hours. Cu-IUD insertion within 5 days is the most effective emergency contraceptive method.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.