Postinor-2 is an emergency contraceptive only. Postinor-2 is not intended as a regular method of contraception. It is used to prevent pregnancy when taken within 72 hours of unprotected intercourse. It is estimated that Postinor-2 will prevent 85% of expected pregnancies. 95% of expected pregnancies will be prevented if taken within the first 24 hours, declining to 58% if taken between 48 hours and 72 hours after unprotected intercourse.