Hello Thanks for writing to us with your health concern. Apart from a pregnancy there are various other factors that can cause menstrual delay. Stress, anxiety, tensions, weight gain, ingestion of hormonal medications ( such as the emergency contraceptive pill ECP ), travelling, late nights etc are some reasons. Alteration in thyroid hormone dysfunction and PCOS - polycystic ovarian syndrome also can cause such a picture. In this case, unwanted 72 offers almost more than 90 % protection against pregnancy. So your friend is reasonably well protected. However, the ECP has a side effect of preponing or postponing the expected normal periods by seven days or more, sometimes a week. Hence the menstrual delay most probably would be caused by the intake of the ECP. Right now , just wait and watch If she does not have a proper period within the next two weeks, please take a pregnancy test. All the best. Take care.