The main reason is that after intercourse, the sperm will quickly enter the uterine cavity and reach the fallopian tubes, and if ovulation has already occurred, the sperm and egg will combine to form a fertilized egg, but the fertilized egg will not immediately enter the uterine cavity to lay, but will only enter the uterine cavity to lay after about ten days, and the uterine lining has already been repaired, so most of them will not The endometrium has already been repaired, so most of them will not affect the fertilized egg, which will grow and develop after it is laid. However, if there is bleeding during ovulation, intercourse is not recommended because it may lead to reproductive tract infection. It is best to keep the area clean and change the sanitary napkins regularly to reduce the possibility of infection. If you plan to get pregnant, wait until the next time you have intercourse during ovulation.