Bad Habit 1: Sexual intercourse during menstruation – pelvic inflammatory disease – infertility. From the perspective of women\’s health, sexual intercourse during menstruation is not advisable. Because normally, the cervix is closed and bacteria cannot enter the pelvic cavity, but during menstruation, the cervix will relax and its protective ability will decrease. If you have sex at this time, bacteria and blood can easily enter the pelvic cavity and cause pelvic inflammation. What\’s more serious is that it can also cause endometriosis in the future. Both are infertile