is is a single dose emergency contraceptive
that provides a safe and easy way to prevent unplanned pregnancy
after unprotected sex if taken within 72 hrs.The chances of failure are if the dose taken is delayed to after 72 hrs.It should not be taken later than 72 hours.If you take the ipill within 24 hours of unprotected sex, is is 95% effective.The ipill is ineffective if the patient is already pregnant. It will not end a pregnancy that has already begun.
The ipill prevents the ovulation, fertilization or implantation
of the egg in the uterus
and thus prevent pregnancy.
The chances of pregnancy are less in your case since you gave her within 72 hrs after sexual intercourse.