Hello dear Understand your concern Chance of pregnancy is only 5 % But period may be delayed due to side effects of the unwanted 72 because of hormonal imbalance. Unwanted 72, contain synthetic progestin, Levonorgestrel. It is intended for the following uses: Unplanned intercourse in couples that are steady or married Failed measures of contraception For this emergency contraception to be effective, it is necessary to take one 1.5 mg pill of Levonorgestrel on a single day and within 72 hours of unprotected intercourse. Best results are seen when Unwanted 72 is taken quickly, within 72 hours of an event, as it takes 72 hours after fertilization for a woman’s body to produce a pregnancy. The level of protection provided by Unwanted 72 is as follows: If taken - within 24 hours – up to 95% effective If a woman should vomit after taking Unwanted 72, it is recommended to repeat the one time dose for effectiveness in pregnancy prevention under the direction of a healthcare provider. So it may be ineffective in 5%. So please confirm pregnancy by 1. Blood HCG level today only. It is very sensitive. 2. Urine pregnancy test: after 7- 8 days 3. USG Hope this may help you. Best regards Dr. Sagar