What could be the reason for a delay of four or five days in menstruation? I'm not pregnant either.

Patient's question:

Patient Gender: Female
Patient Age: 34
Menstruation is delayed by four or five days, what's going on? I'm not pregnant either.

Doctor's answer:

Premenstrual, retrogression of one week is normal. Fatigue, medication, and endocrine changes can all cause irregular menstruation. If menstruation does not occur for more than 10 days or longer, and pregnancy is ruled out, it should be considered as menstrual disorder and an endocrine examination is needed to identify the cause.