Merck Manual

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How Effective Is Emergency Contraception?

How Effective Is Emergency Contraception?

Method

Percentage of Women Who Become Pregnant Because Emergency Contraception Is Unsuccessful

Copper-releasing IUD

0.1%

Levonorgestrel-releasing IUD (high dose)

0.3%

Levonorgestrel taken by mouth

2–3%

Ulipristal acetate (a single dose)

1.5%

IUD = intrauterine device.