If a woman with a normal period has a delayed period for four days, the details are as follows: 1. Pregnancy: The most important reason to know is whether or not you are pregnant, because pregnancy is the most common cause of delayed periods in women of childbearing age, and you can determine whether or not you are pregnant by doing a urine test for early pregnancy or by drawing blood for HCG. 2. For example, endocrine disorders, poor rest, mental stress, emotional instability, malnutrition caused by excessive dieting and weight loss, etc. may interfere with the regularity of menstruation, so after ruling out pregnancy, it is important to look for reasons from these aspects. Usually no menstruation for more than seven days and it is determined that there is no pregnancy, it is recommended to go to the hospital for further examination to assess the condition of the uterus and the thickness of the endometrium.