Folic acid can interfere with the normal endocrine function of women, for example, folic acid may affect the content of estrogen, sex hormone, progesterone and luteinizing hormone in the body, because these hormones have a very close relationship with the formation and excretion process of menstruation, when the level of these hormones is abnormal, it may also lead to delayed menstruation. When the level of these hormones is abnormal, it may lead to delayed menstruation. Second, the side effects of folic acid are caused by the relatively slow metabolism of folic acid in the body. If women take a large amount of folic acid, it may cause the accumulation of folic acid in the body and eventually interfere with the normal physiological function of the endometrium or the vagina, resulting in delayed menstruation. Third, folic acid can cause abnormal function of the nervous system, because the formation of menstruation also needs the participation of the nervous system, if the nervous system function abnormality will also appear the phenomenon of delayed menstruation.