Ovulatory bleeding is not menstruation. Ovulatory bleeding is due to a brief drop in estrogen levels after ovulation, which leads to partial exfoliation of the endometrium and vaginal bleeding due to loss of hormonal support. Generally, this bleeding does not exceed seven days and most lasts 1-3 days, and the symptoms can be improved by inhibiting ovulation, regulating the cycle, and improving the symptoms through the oral combination of short-acting contraceptives. What we usually call menstruation refers to the cyclic shedding and bleeding of the endometrium as the ovaries change cyclically, resulting in changes in estrogen. The average menstrual cycle is 21-35 days, and the normal menstrual period lasts for an average of 4-6 days, with a volume of 20-60 ml. There are usually no special symptoms during menstruation, but some women may experience lower abdominal and lumbar discomfort or diarrhea due to pelvic congestion and prostate action.