The interval between the first and second menstruation is usually 28-30 days, which is considered a normal cycle, but because every woman’s cycle is different, and the endocrine hormones will have certain changes, you can have a period once every 40 or 50 days, but the most important thing is that every time there will be such a long time between periods, which is considered a normal cycle, and there is no need to be overly nervous. Some women deliberately use medication to regulate to 30 days, when the medication is stopped can still return to 40 days or 50 days, 40 days or 50 days is also considered a normal cycle, will not affect the reproductive health and physical health. Some women will have irregular menstrual cycles, for example, this time it is 25 days, the next time it will be 40 days, we need to analyze what is the cause through ultrasound, including endocrine hormone blood tests, so that we can use the right medication for the symptoms.