Women should not have sex during their menstrual period. Menstruation is a very special period for women and a stage of low resistance. Menstrual blood has a large number of broken red blood cells inside, and these red blood cells are the best culture medium for bacteria. If you have sex during this period, it will easily lead to pelvic-vaginal infection, which will cause vaginitis, endometritis and endometriosis. It has an effect on the woman’s body, plus it may affect the regularity of her menstruation in the future, while this condition is also bad for the male genitals.