If the menstrual cycle is normally normal, the days before the menstrual period are generally considered safe and less likely to result in pregnancy, but this cannot be generalized. The first thing you need to do is to make a determination based on the woman’s menstrual cycle. Once an egg is not fertilized, it degenerates into the corpus luteum (the function of the corpus luteum is to secrete luteinizing hormone). The corpus luteum begins to shrink 9-10 days after ovulation and the amount of luteinizing hormone secretion decreases. When the luteal phase is reached after ovulation, the egg has already withered, so for women with normal menstrual cycles, it is not easy to conceive a few days before the onset of menstruation, which is usually referred to as the safe period. However, women should also note that the safe period is not safe. For women with irregular menstruation, it is not easy to determine the time of the next menstrual period, so it is also not easy to determine the safe period.