Usually women have a menstrual cycle of 21-35 days, and some women may have a longer menstrual cycle, which can reach about 40 days. If this state persists, it can generally be considered as normal. However, if there is a delay of 10 days or a sudden phase of the above situation, it is generally considered to be due to abnormal secretion of estrogen and progesterone, and there are several common causes as follows: 1. Pregnancy: Women of childbearing age who have regular menstruation, in the case of sexual life, the delay of menstruation for 10 days should first consider whether it is pregnancy. This can be confirmed by early pregnancy test paper or blood or urine HCG test at the hospital. 2. mental environment factors: when women are overly stressed and overly nervous, or when their weight suddenly increases or decreases due to environmental reasons, it may cause estrogen and progesterone secretion disorders, resulting in menstrual delay for ten days. 3. drug factors: if you have recently taken drugs containing hormones (such as progesterone tablets, etc.), it may also lead to 4. Disease factors: Hypothyroidism, polycystic ovary syndrome or premature ovarian failure, hyperlactation syndrome and other diseases may lead to endocrine system disorders, resulting in delayed menstruation or less hair. In this case, a clear diagnosis is needed by performing thyroid function and female sex hormone testing.