If the period has always been 3 days in the past, it is a relatively normal phenomenon to lose your period after 3 days. However, if the period has always been longer than 3 days and has only recently shortened to 3 days, this is an abnormal phenomenon. The menstrual period varies from person to person and it is not necessarily a problem if it is always 3 days. As long as the volume of menstruation reaches 30-50ml and is very regular, a menstrual cycle of 21-35 days is normal. However, if the menstrual period has always been more than 3 days, but recently it has been shortened to 3 days, it is a sign of menstrual disorder, which may be caused by endocrine disorder, luteinizing insufficiency, ovarian hypofunction, gynecological inflammation and so on. It is recommended that patients first self-regulate, pay attention to rest, keep warm, keep a happy mood and eat less spicy and stimulating diet. If the improvement is not obvious, you can go to the gynecology department of the hospital 2-4 days after the next menstrual period to take blood test and perform sex hormone six test to confirm the diagnosis and treat the symptoms.