HI, thanks for using healthcare magic
The risk can vary according to where the woman is in her menstrual cycle at the time of intercourse. If she was close to the time when she would have ovulated or had already ovulated then it does not work as well.
Ovulation generally occurs 10 to 17 days since the onset of the last period. It varies from woman to woman.
In general , the effectiveness is high if taken within 12 hrs which was done.
The effective is approximately 75% which means that it reduces the number of women who would have conceived by 75 %.
If the periods are delayed you would have to do a pregnancy
test to determine if comception took place.
If this is not the case, then the two of you may want to consider using regular contraception
such as oral contraceptive
pill, injection, condoms, the patch. There are different formulations that you can consider.
I hope this helps