[Caelligh]

It works that way in rare cases - just like every form of hormone contraception. It's wrong, however, to say that it's "too late" to prevent ovulation after sex. You do need to act fast, though. That's what makes it emergency contraception, and why it's so important to have easy, local access to it.

[etlib]

It works that way in rare cases - just like every form of hormone contraception. It's wrong, however, to say that it's "too late" to prevent ovulation after sex.

If plan B works only by preventing ovulation it would be pretty much worthless. Your supposed "rare case" is the usual case when pregnancy results.