When brown blood appears in women after intercourse, the following causes should be considered: 1. If it is already in the menstrual period and the bleeding is slowly increasing, consider it to be a physiological manifestation of menstruation, just when intercourse happens to be in the menstrual period. 2. If this occurs at the time of ovulation, consider it to be caused by ovulatory bleeding, which is caused by a small amount of endometrial flaking due to the fluctuating drop of estrogen during ovulation. 3, If it is not cervical bleeding but localized cervical bleeding, it is considered to be caused by cervical lesions, most commonly cervical inflammation, cervical polyps, or even cervical intraepithelial neoplasia. If bleeding occurs repeatedly after intercourse, it is also necessary to rule out whether it is caused by cervical cancer.