There can be a number of causes for a 3-day delay in menstruation. If you have uncontraceptive intercourse during the month, there may be a chance of pregnancy, so it is important to rule out whether there is a pregnancy or not. When hysteroscopic surgery or examination is performed, there will be certain complications, such as adhesions in the uterine cavity, resulting in blockage of menstrual blood, there will be delayed menstruation. Disease causes, when there are uterine fibroids, ovarian cysts, pelvic inflammatory disease, can lead to delayed menstruation. Oral medication, such as oral emergency contraceptive pills, can cause endocrine hormone imbalance in the body, and there may also be delayed menstruation. If the mental stress of the month is relatively high and too stressful, it will affect the endocrine hormones and may also cause delayed menstruation. It is normal for menstruation to be delayed for 3-7 days, and it is recommended that you can be patient and wait for your period, as long as it comes within 7 days, there is no big problem.