Hello, I have gone through your query and understood the concern. When hormones are taken to postpone the menstrual cycle, the ovulation can get disturbed and may not happen at all depending on the timing of the pill intake. In addition, the intake of the emergency pill creates disruption of the hormone milieu. This in itself delays the next natural period by a week or two. If she becomes overdue, she needs to see a specialist for further management. A pregnancy test, preferably the blood test, is then done along with a pelvic/trans-vaginal sonogram and treatment planned accordingly. Hope this helps.