The probability of getting pregnant is almost zero because most of the semen will be expelled from the body with the menstrual blood if you have intercourse during the physiological period. In addition, some of the sperm will enter the uterine cavity and reach the fallopian tubes, then the survival time is 3 days. As the menstrual period is in the follicular phase, there is no dominant follicle and there is no ovulation, so the sperm will die naturally after 3 days of survival without combining with the egg, so the chance of pregnancy is almost 0. It is also recommended that you should not have sex during your menstrual period, mainly because sex can lead to inflammatory reactions in the reproductive tract due to the infection of pathogenic bacteria. In addition, if you have sex, it may also cause the possibility of endometriosis, so don’t have sex when you are on your period.