The main reason for vaginal bleeding is that the front and back walls of the vagina do not fit together and air enters and exits the vagina, resulting in a sound similar to a fart. This condition is clinically known as pussy blowing, which is mainly caused by the following reasons: 1. After vaginal delivery, the dewlap is caused by the long-term compression of the pelvic floor during vaginal delivery, which reduces the muscle tone of the pelvic floor and leads to the relaxation of the vaginal wall, which causes the front and back walls of the vagina to fail to fit together, resulting in this condition. 2. The body is thin and the fat of the pelvic floor is relatively low. 3. The vaginal wall may also become lax due to aging of the organs.