A woman’s menstrual cycle ranges from 21 to 35 days, within which it is normal. On average, a woman’s menstrual cycle lasts 28 days, but it is normal for menstruation to occur 1 week earlier or later due to individual physical, genetic and environmental factors. If the menstrual cycle is less than 21 days, it may be due to ovarian dysfunction or luteal insufficiency. If the menstrual cycle is longer than 35 days, it may be related to polycystic ovary syndrome or low estrogen. Occasional long or short menstrual cycles may be related to stress, environmental factors, etc., and may regulate themselves to normal after active improvement, so there is no need to worry too much. If the menstrual cycle is too long or too short for a long period of time, it is recommended to consult an Obstetrician and Gynecologist to find out the cause of the problem and take active treatment. It is recommended that women pay attention to menstrual hygiene during menstruation and change sanitary napkins frequently. At the same time, relax, avoid exertion, and pay attention to supplemental nutrition.