Blood in the mouth every day may be periodontitis, leukemia gingival lesions, gingivitis in pregnancy and other diseases caused by the following. 1. Periodontitis: Gums may bleed after brushing or biting hard objects in the early stage of periodontitis, and with the development of periodontal inflammation, spontaneous bleeding may occur. 2. Gingival lesions of leukemia: it can affect the gingival papilla, gingival margin and attached gingiva, the gums have obvious bleeding tendency, the gingival margin is often oozing blood, and the bleeding is not easy to stop, and at the same time, it can be seen that the gingiva and the oral mucosa have bleeding spots or petechiae. 3. Gingivitis in pregnancy: occurs in women during pregnancy, manifested as individual gums or the whole mouth of the gums of the gingival margin and gingival papilla bright red or dark red, soft texture, swelling and hypertrophy, easy to bleed when touching, sucking, eating. There may be other reasons for blood in the mouth every day, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease and then targeted treatment.