Final answer:
Morning-after pills must be taken within 72 hours of unprotected intercourse to prevent pregnancy.
Step-by-step explanation:
To prevent pregnancy, morning-after pills must be taken within 72 hours of unprotected intercourse. Emergency contraception can be taken as a single-pill dose or two-pill dose, and it is available over-the-counter (OTC) for women ages 17 and older. The morning-after pill works by stopping the ovaries from releasing an egg or keeping the sperm from joining with the egg.