The main reason why you can’t get pregnant when you have intercourse on the 2nd day of your period is because: 1. semen will be discharged out of the vagina in large quantities with the menstrual blood, reducing the possibility of pregnancy; 2. most of the ovulation is in the middle of the period, and even if the sperm can reach the fallopian tube at this time, the survival time is at most 3 days, and there is no ovulation after death, so you won’t get pregnant. Therefore, pregnancy will not occur. It is recommended not to have intercourse during menstruation because it may lead to inflammatory reactions in the reproductive tract, which may cause increased vaginal discharge, recurrent lower abdominal pain or endometriosis.