The second bleeding after a clean period is usually not a real period, but vaginal bleeding due to other reasons. The main reasons for this phenomenon include: 1. Ovulation bleeding. If the bleeding occurs in the middle of two menstrual cycles, it is usually a sign of ovulation bleeding. The amount of bleeding is not much and the bleeding time is not long enough to require special treatment, and most of them can be cleaned by themselves; 2. contact bleeding, if the bleeding occurs because of the stimulation of sexual life, it is contact bleeding, mainly due to cervical erosion, cervical polyps, cervical cancer and other abnormal manifestations caused by various cervical diseases; 3. abnormal bleeding caused by ovarian endocrine function, if the bleeding time is not related to the menstrual cycle exact relationship with the menstrual cycle and no relationship with sexual life, and there are no diseases such as uterine fibroids, endometrial polyps or cervical lesions after ultrasound examination, then it is mostly abnormal bleeding caused by endocrine function disorder of the ovaries.