Also called Plan B, emergency contraception consists of two pills containing levonorgestrel that are ingested as soon as possible after sexual intercourse. The sooner they are taken, the more effective they are at preventing pregnancy.  Emergency contraception is available at most pharmacies and from your healthcare provider. Emergency contraception should not be a replacement for regular birth control; it's a last resort to be take after unprotected sex.

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Write a summary of the previous text in Vietnamese:
Sử dụng biện pháp tránh thai khẩn cấp.