A 4-day delay in menstruation may be normal, or it may be due to pregnancy or endocrine disorders. The normal menstrual cycle for women is 21-35 days, and a few days early or late is within the normal range. However, if you are sexually active, the absence of menstruation may indicate that you are pregnant. 1. Pregnancy: A 4-day delay in menstruation may indicate pregnancy. After pregnancy, the ovaries will not secrete estrogen and progesterone periodically, and the endometrium will not undergo cyclic changes, which will be manifested as a phase of menopause. It is recommended to go to the hospital for HCG test for 7-10 days after menopause. 2. Endocrine disorders: the endometrium is affected by the estrogen and progesterone secreted by the ovaries to function normally. If there are situations such as stressful life and late night, it may lead to the imbalance of the estrogen and progesterone secretion, which will delay the menstruation. It is recommended to go to the hospital for hormone six tests. Delayed menstruation for 4 days may also have other reasons, it is recommended to observe, if the menstrual cycle more than 35 days, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.