You will not get pregnant during menstruation for the following reasons: 1. Menstruation is due to the ovaries discharging eggs because the eggs do not combine with sperm to form a fertilized egg. The estrogen secreted by the ovaries starts to decline and cannot maintain the endometrium to continue to thicken, the thickened endometrium will then shed, and after shedding the local capillaries rupture and bleed to form menstruation. So there are no mature follicles discharging eggs during menstruation and there is no chance of pregnancy. 2. After the endometrium is shed during menstruation, the uterine wall is traumatized and the endometrium is so thin that even if an egg and sperm combine to form a fertilized egg, the fertilized egg cannot be laid in the uterine wall, so there will be no pregnancy during menstruation. 3. After intercourse during menstruation, because sex will lead to faster pelvic blood circulation, the amount of menstrual blood increases The semen in the vagina will be quickly washed away by the menstrual blood, so it is not easy to enter the fallopian tube to unite with the egg.