The causes of red and swollen gums in one-year-old babies are as follows: 1, the mucous membrane of the gums is fragile in texture, and frequent thumb-sucking, nibbling on rubber nipples or toys can easily damage the mucous membrane and produce superficial ulcers, which are prone to erosion.2, parents help their babies to scrub the gums of the mouth, and if they exert too much force, the mucous membrane can be damaged, resulting in redness and swelling.3, a large amount of food residues and soft tartar adheres around the crowns of newly-erupted teeth, which causes bacterial infections, and can produce significant 4, teeth in the process of eruption part of the gums remain and cover the tooth surface, in chewing the bite, resulting in swelling and pain. 5, milk teeth early caries, the formation of residual roots and crowns, sharp edges will stimulate the gums to swell repeatedly.