When is the ovulation period for the period that came on the 31st, it has a certain relationship with whether the individual’s menstrual cycle is regular or not, and should be analyzed specifically, not generalized. For people with regular menstrual cycles, you can calculate the ovulation period from the first day of the last menstrual period for about 15 days. Before ovulation, there is usually a significant increase in vaginal leukorrhea, which is an important signal of impending ovulation. If a woman has her period on the 31st, she will usually ovulate on the 14th of the following month. However, if a woman’s menstrual cycle is irregular, ovulation may not necessarily occur on the 14th, but may be delayed or advanced. If a woman’s menstrual cycle is usually less than 28 days, ovulation usually occurs earlier, and if her menstrual cycle is usually more than 28 days, it may be pushed back. Therefore, for people with irregular menstrual cycles, follicle monitoring can be performed 10 days after the onset of menstruation, and a strong positive reaction indicates that ovulation is imminent.