If you had unprotected sex before you started using up birth control.It does not work the same way the plan b pill works.

You should not take loestrin 24 Fe now until your next period starts. If you read the directions it will tell you when to start taking them. If you did indeed become pregnant the night u had unprotected sex, it is not safe to take this birth control now. This is why anytime u start to use a new form of birth control. Whatever the form it may be that you choose. You always should use a second form of birth control such as a condom for the first 2-3 days after you first start taking your pill.