A woman’s menstrual cycle is calculated from the first day of her menstrual period to the first day of her next period. Usually, most women have a menstrual cycle of 28 to 30 days, and normally ovulation occurs in the middle of each period. Some people may have a longer menstrual cycle, while others may have a shorter one, which is mainly due to individual differences in clinical practice. For example, if the menstrual cycle is 25 days, it is normal. If the menstrual cycle is once every 35 days, as long as the menstrual volume, color, and time of menstruation do not change, it is normal. It is recommended to keep warm during menstruation and to pay proper attention to diet when menstruating.