If the period does not come on time, the most common reasons are the following: 1, endocrine disorders, increased work pressure, or tension, anxiety, insomnia, may lead to endocrine disorders, causing menstrual cycle disorders, you can check the sex hormone six to understand, according to the results to give treatment, preferably in the 2-3 days of the period to draw blood test; 2, polycystic ovary syndrome, if suffering from polycystic ovary syndrome, menstruation will appear delayed phenomenon, and the patient will appear weight gain, hairy phenomenon; 3, ovarian function decline will also make the menstrual cycle disorders.