A woman should not have intercourse on the 3rd day of her period when her menstrual flow is very light. Although the amount of menstruation is small, it means that menstruation is still not completely finished. If you have intercourse, the presence of blood in the vagina will breed bacteria, leading to bacterial infection, and the retrograde flow of bacteria will trigger the development of pelvic inflammatory disease and endometritis in women. If the menstrual blood flows backward, it may trigger women to develop endometriosis, so it is best for women to have intercourse after the end of menstruation. Women in the menstrual period, must pay attention to personal hygiene, but also pay attention to more rest, can not be too fatigue, avoid spicy and stimulating food.